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The Powercrank Thread

So lets get some serious discussion going about Powercranks. An independent crank system that makes the claim with 6-9 months of full immersion training that users will see a 40% improvement in power.

Powercranks (also briefly sold under the brand name Smart Cranks) are marketed as a training tool and have been the subject of several well performed studies published in quality journals like the European Journal of Applied Physiology and some lesser journals like Journal of Strength and Conditioning Research.

Many claims have been made about various riders using the cranks but none of their testing data has been made available to show if these claims have any merit. Some of the claims from riders have been backed with data but this data has in cases been shown to have been tampered with and in other cases the measurement is suspect due to a poorly calibrated power meter.

The rest of the support for a Independent Crank system comes from anecdotal evidence from riders claiming they felt a benefit from the system. Always hard to assess these claims as there is no control carrying out a similar workload using a normal crank to make a reasonable comparison. Also hard to rule out any third variable that could be causing a change in performance. One study led by Dixon and associates showed a marked improvement in power and VO2max but there was no control group to show if the same gains could be made by using a normal crank.

All of the published studies on independent cranking systems have found no significant change in cycling performance or cycling fitness after a period of 5-6 weeks. I will list all the current studies and their abstracts. Try Google Scholar to see if any of the studies are available in full text as often the abstract is heavy on the results section but light on the methods to determine if the research design was adequate. This obviously limits the utility of presentations made at conferences that were not published in academic journals and only the abstract is available.

It is clear from those with an understanding of exercise physiology and sports training science that the human body responds to the exercise stimulus instantly and adaptations to a period of training are rapid. The time period of 5-6 weeks is more than adequate to see any expected adaptations to a training stimulus and numerous training, dietary, recovery, psychological and biomechanical studies have seen significant changes in less than 2 weeks.

This runs counter to the claims of independent crank system manufacturers who state that the real adaptations occur after 6-9 months of full immersion training. Were these claims true and people who trained with a independent crank system who achieved a 40% improvement in power; we would expect to see these riders dominate the sport to an extent never seen before.

A 40% gain for an average cyclist who could produce 300 watts for a 40km TT would see them produce 420 watts. This equates to ~6mins over 40km. Of course what would be hard to separate is whether it is the independent crank system or the type of training performed that led to the improvement. This is why it is crucial to test any independent crank claim against a control group performing the same training using normal cranks.

There has been no evidence provided that any cyclist has even achieved this mythical 40% improvement in power even with independent cranks being available for the last 13 years. Various anecdotal reports have been made but the metrics used to determine a change in performance were not true performance measures.

One anecdotal claims was a 2 mile per hour increase in speed during a 2000 metre pursuit. A change in speed can be affected by many variables. Temperature, wind speed, wind direction, humidity, time of the season, competitive variables, training, equipment selection, bike position, flexibility, riding line on the track and many others. Even on an indoor track weather, even within a session, can have an influence in performances.

In 2008 an quasi-scientific study was attempted on the Slowtwitch.com website. Here is the report from one subject who measured his progress with a power meter while carrying out training with a independent crank system.

http://james-p-smith.blogspot.co.nz/2008_06_01_archive.html

While you read this I will upload the many independent crank system studies that have been performed.
 
1293 Board #32__ May 28 11:00 AM - 12:30 PM
The Impact of 10 weeks of Independent Cycle Crank use on
Run Performance
Alicia Diaz, Robert M. Otto, FACSM, Christopher Kushner, Jessica
Marra, Laura Walsh, Carolyn Richardson, John W. Wygand. Adelphi
University, Garden City, NY.
Email: wygand@adelphi.edu
(No relationships reported)
Enhanced endurance run performance is usually associated with improved aerobic power
and run efficiency resulting from high intensity, tempo, interval, and/or long slow distance
run training. However improvement in run performance has been reported in triathletes
from cycle training, despite the contradiction to principles of specificity.
PURPOSE: The purpose was to evaluate the effect of ten weeks of independent cycle
crank (ICC) training on run performance as measured by oxygen efficiency (OxE),
time trial performance (TT), and leg strength
METHODS: After a medical/health screening, thirty triathletes (16 male, 14 female)
(age 43.2 [range 25-54 yr], ht 176 [range 160-188 cm], and body mass 73.3 [range
54.3-97.7.5 kg]), participated in familiarization trials including leg strength (LE [leg
extension], LF [leg flexion]), and treadmill based steady state OxE (mLO2/kg-meter)
trial and a 5 K time trial. Identical testing was performed during the familiarization
trial, pre-test (within one week) and the post-test (ten weeks later). After the pre-test
trial, subjects were randomly assigned to one of three groups (C = control, 90 = 90
min/wk and 180 = min/wk). For ten weeks all subjects exercised (swim, cycle, run) a
minimum of eight hours each week. All groups ran a minimum of 2.5 hours/week at
low-moderate intensity (<75% HRR) and cycled a minimum of three hours/week with
C in fixed cranks, 90 for 90 min fixed and 90 min ICC, and 180 for 180 min ICC.
RESULTS: Changes of -3.8%, -6.2%,and -0.8% in OxE, -4.0%, -5.3%, and -0.4% in
TT, 7.1%, 8.8%, and 3.2% for LE, and 5.4%, 6.5%, and 5.5%, were evident for the
C, 90 and180 groups, respectively. Statistical analysis by ANOVA (P<.05) reveals no
significant difference among groups or pre-post changes within groups, except group
90 significantly improved run efficiency (OxE).
CONCLUSION: Ten weeks of winter time, base training for seasoned triathletes
reveals subtle changes that for the most part are not statistically significant. Although
self report indicates perceived improvement, the principle of specificity is upheld with
little influence of independent cycle crank arm use on run or strength performance.
 
The Impact of 10 weeks of Independent Cycle Crank use on
Cycle Performance
Robert M. Otto, FACSM, Laura Walsh, Jessica Marra, Christopher
Kushner, Alicia Diaz, Carolyn Richardson, John W. Wygand.
Adelphi University, Garden City, NY.
Email: otto@adelphi.edu
(No relationships reported)
Improvements in cycle performance may be a result of enhanced efficiency and/or a greater
power output. Cyclists strive to achieve both by over-distance training, high intensity
training, and specific cycle drills. Special products that claim to improve performance
by offering improved aerodynamics, reduced total cycle mass, better force transfer to the
crank, or providing biomechanical feedback rely on a paucity of research.
PURPOSE: To evaluate the effect of ten weeks of using independent cycle cranks
(ICC) on cycling performance as measured by oxygen efficiency (OxE), time trial
performance (TT), and body composition (BC).
METHODS: After a medical/health screening, thirty triathletes (16 male, 14 female)
(age 43.2 [range 25-54 yr], ht 176 [range 160-188 cm], and body mass 73.3 [range
54.3-97.7.5 kg]), participated in familiarization trials including DEXA scan, electronic
cycle ergometer based steady state OxE trial and a time trial. Identical testing was
performed during the familiarization trial, pre-test (within one week) and the posttest
(ten weeks later). After the pre-test trial, subjects were randomly assigned to one
of three groups (C = control, 90 = 90 min/wk and 180 = min/wk). For ten weeks all
subjects exercised (swim, cycle, run) a minimum of eight hours per week. All groups
cycled a minimum of three hours/week with C in fixed cranks, 90 for 90 min fixed and
90 min ICC, and 180 for 180 min ICC.
RESULTS: Statistical analysis by ANOVA (P<.05) reveals no significant difference among or
between trials.
CONCLUSION: The use of independent cycle crank arms for a maximum of 30 hours
within ten weeks, requires the user to apply force independent of crank position, but
does not result in quantifiable changes in cycle efficiency or performance
 
Physiological responses to training using PowerCranks on trained cyclists.
Stephen J. Dixon, Michael F. Harrison, Kenneth A. Seaman, Stephen S. Cheung and J. Patrick Neary. University of New Brunswick, Fredericton, NB; Dalhousie University, Halifax, NS; University of Regina, Regina, SK

ABSTRACT

PowerCranks are cycling cranks that are independent of each other, requiring force application throughout the pedal stroke, theoretically increasing muscle recruitment and stimulus in the legs. This study examined the physiological adaptations to PowerCranks, and the time course of responses in maximal and submaximal cycling performance. Eight Trained cyclists (35.1 ± 6.8 yr) participated in 6 wks of 100% immersion training using solely PowerCranks, consisting of ~8 h/wk of aerobic and anaerobic (~80:20) cycling training. A continuous incremental cycling test to exhaustion (50 W increase every 2 min) was performed prior to and following the training program using normal cranks. In addition, 10 min of submaximal cycling (70% of VO2max wattage) were performed with both normal cranks and PowerCranks at an approximate cadence of 85 rpm, pre and post training. VO2max increased 15.6% (58.1 ± 5.8 to 67.3 ± 6.6, P=0.013). Maximum power increased 11.6% (316.7 ± 25.8 to 358.3 ± 20.4, P=0.011) following PowerCranks training. In summary, our data suggest that PowerCranks increased maximal aerobic capacity and power in trained cyclists.
 
Journal of Strength and Conditioning Research, 2003, 17(4), 785–791

Effects of Short-Term Training Using Powercranks
on Cardiovascular Fitness and Cycling Efficiency
MARK D. LUTTRELL AND JEFFREY A. POTTEIGER

ABSTRACT
Powercranks use a specially designed clutch to promote independent
pedal work by each leg during cycling. We examined
the effects of 6 wk of training on cyclists using Powercranks
(n 5 6) or normal cranks (n 5 6) on maximal oxygen
consumption (VO2max) and anaerobic threshold (AT)
during a graded exercise test (GXT), and heart rate (HR),
oxygen consumption (VO2), respiratory exchange ratio
(RER), and gross efficiency (GE) during a 1-hour submaximal
ride at a constant load. Subjects trained at 70% of
VO2max for 1 h·d21, 3 d·wk21, for 6 weeks. The GXT and 1-
hour submaximal ride were performed using normal cranks
pretraining and posttraining. The 1-hour submaximal ride
was performed at an intensity equal to approximately 69%
of pretraining VO2max with VO2, RER, GE, and HR determined
at 15-minute intervals during the ride. No differences
were observed between or within groups for VO2max or AT
during the GXT. The Powercranks group had significantly
higher GE values than the normal cranks group (23.6 6 1.3%
versus 21.3 6 1.7%, and 23.9 6 1.4% versus 21.0 6 1.9% at
45 and 60 min, respectively), and significantly lower HR at
30, 45, and 60 minutes and VO2 at 45 and 60 minutes during
the 1-hour submaximal ride posttraining. It appears that 6
weeks of training with Powercranks induced physiological
adaptations that reduced energy expenditure during a 1-
hour submaximal ride.
 
Effect of Independent Cycle Crank Training on Running
Economy and VO2 Max in Distance Runners

Dale R. Wagner, Edward M. Heath, Aaron W. Smith

ABSTRACT
Wagner DR, Heath EM, Smith AW. Effect of Independent Cycle
Crank Training on Running Economy and VO2 Max in Distance
Runners. JEPonline 2013;16(1):1-9. The purpose of this study was to
examine the changes in running economy and maximal oxygen
consumption (VO2 max) of cross-country runners with cross-training
on the PowerCranks™. Seven men and 6 women completed 6 wks of
stationary cycle ergometer training using either the PowerCranks™ or
the standard cranks (control group). The subjects trained 3 d·wk at
60 rev·min at 3 to 3.5 kg for 30 min, which increased to 40 min after
the 3rd wk and 50 min after the 4th wk, with a 48-h minimum between
training sessions. Pre-and post-running economy and VO2 max were
measured. There were no significant differences in running economy
or VO2 max after training in either the control or the PowerCranks™
group. Further, the difference in change scores for running economy
between the PowerCranks™ (0.102 ± 0.101 L·min) and the control
(0.010 ± 0.108 L·min) groups was not significant (P=0.15).
Crosstraining for 6 wks with independent cycle cranks 3 d·wk
had no effect on the running economy or VO2 max of highly-trained
collegiate distance runners.
 
Strength cycle training: effects on muscular strength and aerobic conditioning.

Journal of Strength and Conditioning Research / National Strength & Conditioning Association [2007, 21(1):178-182]

The strength cycle ergometer has been proposed as a method of simultaneously increasing aerobic conditioning and muscular strength, because of its unique capacity of disengaging the pedal crank, thus allowing for concurrent single-leg cycling. The purpose of this study was to assess the aerobic and muscular strength effects of strength cycle training (SCT), comparing it to similar standard cycle training. A total of 28 recreationally-trained adult subjects (9 men, 19 women) were paired for VO2peak and randomly assigned to either SCT or Monark cycle training (MCT). Subjects trained 3 days per week following a progressive interval protocol for 9 weeks under supervised conditions. Training intervals (5 minutes' duration) consisted of 3 minutes of standard cycling at an intensity of 60-85% of maximum heart rate (HRmax), and 2 minutes of either the disengaged cycling mode (SCT) or standard cycling plus 30 W (MCT). Subjects began training for a total of 25 minutes per session, progressing to 45 minutes per session by study's end. Prior to and following training, subjects were measured for VO2peak; submaximal VO2, heart rate (HR), RPE, power output, and knee and ankle isokinetic strength. Training resulted in significant (p < or = 0.05) increases in VO2peak (14.5%) and submaximal power output (11%), and significant reductions in submaximal VO2, HR, and RPE in both groups. Significant increases in bilateral isokinetic knee extension (4-6%) and left ankle plantar flexion (10.5%) were noted following training in both groups. No group differences were detected in any variable. Although the strength cycle effectively increased aerobic function and resulted in modest selected increases in lower-extremity muscular strength, these changes were not different from those seen using a similar standard cycling protocol.
 
Effects of short-term training using SmartCranks on cycle work distribution and power output during cycling
Harald Böhm, Stefan Siebert, Mark Walsh

European Journal of Applied Physiology
May 2008, Volume 103, Issue 2, pp 225-232

Abstract
SmartCranks use a free running bearing to promote independent pedal work by each leg during cycling. This system is designed for training the upstroke phase during cycling. The effects of training with SmartCranks on the power output (PO) and on cycle work distribution at the anaerobic threshold and the maximum power level were examined. Twenty male, non-professional cyclists were randomly assigned into intervention and control group, training 5 weeks with SmartCranks and conventional cranks, respectively. Before and after the training period the subjects performed an incremental test to exhaustion. Lactate was measured to determine the individual anaerobic threshold (IAT) and forces at the pedal were recorded to quantify changes in the work distribution over the full revolution. We observed no significant statistical difference for peak power (PO; 333.3 ± 32.8 W vs. 323.3 ± 21.8 W) and PO at IAT (229.6 ± 30.1 W vs. 222.7 ± 25.2 W) for SmartCrank and control conditions, respectively (P > 0.05). However, we did observe that work distribution in the downward phase was significantly reduced in the SmartCranks training group at peak PO (from 70.0 ± 4.9% to 64.3 ± 5.8%; P < 0.05). Although the possible implications of the change in the work distribution of sectors are not known, for the success in cycling performance—indicated by the PO—training with the SmartCranks was not more advantageous than training with conventional bicycle cranks.
 
Williams, AD and Selva Raj, I and Stucas, KL and Fell, JW and Dickenson, D and Gregory, JR, Cycling efficiency and performance following short-term training using uncoupled cranks, International Journal of Sports Physiology and Performance , 4, (1) pp. 18-28. ISSN 1555-0265 (2009)

Abstract

Objectives: Uncoupled cycling cranks are designed to remove the ability of one leg to assist the other during the cycling action. It has been suggested that training with this type of crank can increase mechanical efficiency. However, whether these improvements can confer performance enhancement in already well-trained cyclists has not been reported. Method: Fourteen well-trained cyclists (13 males, 1 female; 32.4 ± 8.8 y; 74.5 ± 10.3 kg; Vo2max 60.6 ± 5.5 mL·kg−1·min−1; mean ± SD) participated in this study. Participants were randomized to training on a stationary bicycle using either an uncoupled (n = 7) or traditional crank (n = 7) system. Training involved 1-h sessions, 3 days per week for 6 weeks, and at a heart rate equivalent to 70% of peak power output (PPO) substituted into the training schedule in place of other training. Vo2max, lactate threshold, gross efficiency, and cycling performance were measured before and following the training intervention. Pre- and posttesting was conducted using traditional cranks. Results: No differences were observed between the groups for changes in Vo2max, lactate threshold, gross efficiency, or average power maintained during a 30-minute time trial. Conclusion: Our results indicate that 6 weeks (18 sessions) of training using an uncoupled crank system does not result in changes in any physiological or performance measures in well-trained cyclists.
 
Training With Independent Cranks Alters Muscle Coordination Pattern in Cyclists
Fernández-Peña, Eneko1,2; Lucertini, Francesco1; Ditroilo, Massimiliano1,2

Journal of Strength & Conditioning Research:
September 2009 - Volume 23 - Issue 6 - pp 1764-1772

Abstract
Fernández-Peña, E, Lucertini, F, and Ditroilo, M. Traning with independent cranks alters muscle coordination pattern in cyclists. J Strength Cond Res 23(6): 1764-1772, 2009-In cycling, a circular pedaling action makes the most useful contribution to forward propulsion. Training with independent cranks (IC) has been proposed to improve the pedaling action. The aims of this study were, first, to assess whether the intermuscular coordination pattern of the pedaling action with normal cranks (NC) is modified after a training period with IC and, second, to determine if the new coordination pattern is maintained after a washing-out period. Eighteen cyclists, divided into a control (CG) and an experimental (EG) group, underwent 2 test sessions (T1 and T2) separated by 2 weeks of training (18 hours). The electromyographic (EMG) activity of 4 lower limbs' muscles was recorded while the athletes pedaled at 80 rpm for 60 seconds at 30 and 50% of the maximal power output determined during a maximal pedaling test. The tasks were performed with IC (EG) and NC (EG and CG). The EG underwent a retention test session (T3) after another 18-hour training with NC. EG showed a significant (45.8 ± 8.8 vs. 36.0 ± 6.1%, p < 0.01 at 30% intensity) and a quasi-significant (62.7 ± 10.3 vs. 54.2 ± 8.7%, p = 0.09 at 50% intensity) decrease in vastus lateralis EMG activity and a quasi-significant (36.4 ± 13.4 vs. 43.5 ± 10.9%, p = 0.09 at 30% intensity) and a significant (54.5 ± 12.1 vs. 65.5 ± 16.1%, p < 0.05 at 50% intensity) increase in biceps femoris EMG activity between T1-NC and T2-NC. By T3, EMG activity returned to initial levels (T1). On the contrary, CG did not reveal any significant variation. The results provide scientific support for muscle coordination pattern alteration from the use of IC, potentially achieving a more effective pedaling action. IC training reduces quadriceps exertion, thus preserving it for important moments during competition.
 
EFFECTS OF INDEPENDENT CRANK ARMS AND SLOPE ON PEDALING MECHANICS
S. Hanaki-Martin, D. Mullineaux, S. Underwood

Abstract

The aim of this study was to identify the effects of independent crank arms and slope on pedaling kinetics during an anaerobic maximal-effort cycling bout. After undergoing 6 weeks of training with independent crank arms, each of 6 male cyclists completed four 30 s Wingate tests under different cycling conditions of: fixed crank arms on level surface; fixed crank arms on a slope; independent crank arms on level, and; independent crank arms on a slope. Two-dimensional pedal forces recorded using instrumented pedals were used to derive pedaling effectiveness, work distribution and power output. The effects of the crank arms and the slope were minimal, but highly effective and consistent pedaling force (90% effectiveness, 70% work and effective force of 155±6 N) was observed between 45-135° of the crank cycle in all experimental conditions.
 
The effects of 6-week-decoupled bi-pedal cycling on submaximal and high intensity performance in competitive cyclists and triathletes.
Billy Sperlich · Stefan Zelle · Heinz Kleinöder ·
Matthias Lochmann · Christoph Zinner ·
Hans-Christer Holmberg · Joachim Mester

European Journal of Applied Physiology
August 2011, Volume 111, Issue 8, pp 1625-1630

Abstract
Aim of this work was to examine the effects of decoupled two-legged cycling on (1) submaximal and maximal oxygen uptake, (2) power output at 4 mmol L−1 blood lactate concentration, (3) mean and peak power output during high intensity cycling (30 s sprint) and (4) isometric and dynamic force production of the knee extensor and flexor muscles. 18 highly trained male competitive male cyclists and triathletes (age 24 ± 3 years; body height 179 ± 11 cm; body mass 78 ± 8 kg; peak oxygen uptake 5,070 ± 680 mL min−1) were equally randomized to exercise on a stationary cycle equipped either with decoupled or with traditional crank system. The intervention involved 1 h training sessions, 5 times per week for 6 weeks at a heart rate corresponding to 70% of VO2peak. VO2 at 100, 140, 180, 220 and 260 and power output at 4 mmol L−1 blood lactate were determined during an incremental test. VO2peak was recorded during a ramp protocol. Mean and peak power output were assessed during a 30 s cycle sprint. The maximal voluntary isometric strength of the quadriceps and biceps femoris muscles was obtained using a training machine equipped with a force sensor. No differences were observed between the groups for changes in any variable (P = 0.15–0.90; effect size = 0.00–0.30). Our results demonstrate that a 6 week (30 sessions) training block using decoupled crank systems does not result in changes in any physiological or performance variables in highly trained competitive cyclists.
 
Burns, JM and Peiffer, JJ and Abbiss, CR and Watson, G and Burnett, A and Laursen, PB, Effects of short-term training with uncoupled cranks in trained cyclists, International journal of sports physiology and performance, 7, (2) pp. 113-120.

Abstract

PURPOSE: Manufacturers of uncoupled cycling cranks claim that their use will increase economy of motion and gross efficiency. Purportedly, this occurs by altering the muscle-recruitment patterns contributing to the resistive forces occurring during the recovery phase of the pedal stroke. Uncoupled cranks use an independent-clutch design by which each leg cycles independently of the other (ie, the cranks are not fixed together). However, research examining the efficacy of training with uncoupled cranks is equivocal. The purpose of this study was to determine the effect of short-term training with uncoupled cranks on the performance-related variables economy of motion, gross efficiency, maximal oxygen uptake (VO2max), and muscle-activation patterns. METHODS: Sixteen trained cyclists were matched-paired into either an uncoupled-crank or a normal-crank training group. Both groups performed 5 wk of training on their assigned cranks. Before and after training, participants completed a graded exercise test using normal cranks. Expired gases were collected to determine economy of motion, gross efficiency, and VO2max, while integrated electromyography (iEMG) was used to examine muscle-activation patterns of the vastus lateralis, biceps femoris, and gastrocnemius. RESULTS: No significant changes between groups were observed for economy of motion, gross efficiency, VO2max, or iEMG in the uncoupled- or normal-crank group. CONCLUSIONS: Five weeks of training with uncoupled cycling cranks had no effect on economy of motion, gross efficiency, muscle recruitment, or VO2max compared with training on normal cranks.
 
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Physiological responses to training using PowerCranks on trained cyclists.

Stephen J. Dixon, Michael F. Harrison, Kenneth A. Seaman, Stephen S. Cheung and J. Patrick Neary. University of New Brunswick, Fredericton, NB; Dalhousie University, Halifax, NS; University of Regina, Regina, SK

ABSTRACT

PowerCranks are cycling cranks that are independent of each other, requiring force application throughout the pedal stroke, theoretically increasing muscle recruitment and stimulus in the legs. This study examined the physiological adaptations to PowerCranks, and the time course of responses in maximal and submaximal cycling performance. Eight Trained cyclists (35.1 ± 6.8 yr) participated in 6 wks of 100% immersion training using solely PowerCranks, consisting of ~8 h/wk of aerobic and anaerobic (~80:20) cycling training. A continuous incremental cycling test to exhaustion (50 W increase every 2 min) was performed prior to and following the training program using normal cranks. In addition, 10 min of submaximal cycling (70% of VO2max wattage) were performed with both normal cranks and PowerCranks at an approximate cadence of 85 rpm, pre and post training. VO2max increased 15.6% (58.1 ± 5.8 to 67.3 ± 6.6, P=0.013). Maximum power increased 11.6% (316.7 ± 25.8 to 358.3 ± 20.4, P=0.011) following PowerCranks training. In summary, our data suggest that PowerCranks increased maximal aerobic capacity and power in trained cyclists. Supported by NSERC

Oral presentation at Canadian Society of Exercise Physiologists meeting, November 2006. unpublished.
 
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CoachFergie said:
Effect of Independent Cycle Crank Training on Running
Economy and VO2 Max in Distance Runners

Dale R. Wagner, Edward M. Heath, Aaron W. Smith

ABSTRACT
Wagner DR, Heath EM, Smith AW. Effect of Independent Cycle
Crank Training on Running Economy and VO2 Max in Distance
Runners. JEPonline 2013;16(1):1-9. The purpose of this study was to
examine the changes in running economy and maximal oxygen
consumption (VO2 max) of cross-country runners with cross-training
on the PowerCranks™. Seven men and 6 women completed 6 wks of
stationary cycle ergometer training using either the PowerCranks™ or
the standard cranks (control group). The subjects trained 3 d·wk at
60 rev·min at 3 to 3.5 kg for 30 min, which increased to 40 min after
the 3rd wk and 50 min after the 4th wk, with a 48-h minimum between
training sessions. Pre-and post-running economy and VO2 max were
measured. There were no significant differences in running economy
or VO2 max after training in either the control or the PowerCranks™
group. Further, the difference in change scores for running economy
between the PowerCranks™ (0.102 ± 0.101 L·min) and the control
(0.010 ± 0.108 L·min) groups was not significant (P=0.15).
Crosstraining for 6 wks with independent cycle cranks 3 d·wk
had no effect on the running economy or VO2 max of highly-trained
collegiate distance runners.
Fergie, thanks for this one. I knew the work had been done but had never seen any paper come from it. I am not sure I will make any comments on all the others, because I have done that before and most of the comments are similar as regards all of those negative studies. This also was a negative study but I thought the authors discussion to be much better than usual. In addition, the authors made one comment that makes me believe they actually did this work compared to many of the other studies where this aspect of doing such a study has generally been ignored. To me, it is such a big deal that would interfere with doing such a study and keeping the work loads equal it would seem it would be commented on. In the procedures section they wrote: "Due to the unnatural pedaling motion of the PowerCranksTM, the athletes in the experimental group were not able to initially cycle for 30 min continuously. Short breaks (=40 sec) were permitted, but the total cycling time had to be 30 min. Initially, this adjustment resulted in longer training sessions. Once accustomed to the independent cranks, subjects in the experimental group were able to cycle without breaks."

Edit, there was one aspect of the study design that I think contributed to the failure of this study to see a positive result.
To promote a uniform standard of training for the subjects, a metronome, set at 60 rev·min-1,
was used for both groups throughout the duration of training with the resistance set at 3.0 kg and then
increased to 3.5 kg for the last 3 wks.
When trying to improve running performance we recommend that users concentrate on keeping their cadence at or above their normal running cadence, which for most people is around 90 (180 steps per minute). 60 was way lower than we would have recommended. Perhaps they could have started there but they should have aimed to be at 90 by week 3 or 4 of the study.

Later on, in the discussion, they discuss several aspects of the study that might have led to a negative result where others, such as Luttrell, have seen positive results. Here is what they wrote (emphasis added):
In contrast to cycling, hip and knee flexors have an important role during running, and increased effectiveness of these muscles may increase turnover rate in running. The hip flexors are activated just before and during early leg swing. The leg swing accounts for approximately 20% of the metabolic cost of running (1,18). Additionally, Modica and Kram (18) suggested the knee flexors are active during and at the end of the swing phase. Greater mechanical efficiency, resulting from increased muscle strength and improved motor unit recruitment patterns, are possible explanations for improved running economy (16). Thus, it is logical to conclude that an improvement in running economy results from training of the underutilized leg flexors. In fact, there is some evidence that training the hip flexors can improve running performance. Deane and colleagues (10) reported a 3.8% and 9.0% decrease in 40-yd and shuttle run times, respectively, for physically active college subjects following 8 wks of hip flexion exercises with resistance bands.

In our study, the PowerCranks™ were clearly providing a sufficient stimulus to alter motor unit recruitment patterns to overload the hip flexors. Independent crank cycling decreases vastus lateralis electromyography activity while increasing biceps femoris activity (11), and alters the work distribution pattern of a pedal revolution (3). Actively pulling up on the pedals is an unnatural action, and our highly trained runners were challenged after only a few pedal revolutions of uncoupled cycling during the initial training sessions. Some had to take breaks (19, 10-40 sec breaks in 107 training sessions) in order to accumulate 30 min of cycling exercise until they developed the new muscle coordination pattern.

Despite a logical rationale, training the hip and knee flexors with PowerCranks™ failed to improve the subjects’ running economy or VO2 max. One possible explanation is the high training and fitness status of the subjects. Luttrell and Potteiger (14), the only researchers to report a performance benefit from independent cycle crank training, described their subjects as physically active, cycling at least 2 d·wk-1 with a mean VO2 max value of 56.0 ± 11.5 mL·kg-1·min-1. The cyclists in the other studies (21,24) were described as competitive and trained, riding >6 h or 200 km·wk-1 with a mean VO2 max value >60.6 mL·kg-1·min-1. Similarly, the highly trained competitive distance runners in the present study had a mean VO2 max value of 63.8 ± 9.0 mL·kg-1·min-1. Further, the lower VO2 max values and the wider variability of fitness in Luttrell and Potteiger’s (14) subjects suggest that the training program may have had a bigger effect compared to the more active and better trained subjects of the other studies. Also, it could be possible that for the more active and higher trained endurance athletes, the intervention was not long enough to produce changes in performance measures. It is more difficult to improve economy of motion in highly skilled athletes than novices (20).

Another possible factor that may help explain the results of Luttrell and Potteiger (14) with the present study and the other cycling studies that did not show improvements in performance measures was the difference in the testing procedures. Luttrell and Potteiger (14) investigated a measure of economy throughout a 60-min submaximal ride at 69% of VO2 max. The PowerCrank™ group did not show significantly higher economy than the normal crank group until the 45-min and the 60-min data collections. It is possible that the independent cycle crank group responded better to fatigue than the control group. It is well known that running economy deteriorates and the energy cost of running increases over the duration of a long run (23) or if the athlete is fatigued (17). Therefore, if uncoupled cycling improves muscular endurance of the hip flexors and knee flexors, then, the improvement in running economy might be more obvious if evaluated at the end of a long or fatiguing run.

Strengths of the present study included highly trained athletes as subjects with a built-in control for training done outside the confines of the investigation. It is more difficult to improve the running economy of advanced runners than novice runners, and runners concerned enough about their running economy to train with PowerCranks™ would most likely be advanced. Our sample of collegiate cross-country conference champions fit this profile. Also, since all of the subjects were members of the same team, the run training outside of the research laboratory was identical for both experimental and control groups. Unfortunately, a high percentage of participants (27.8%) failed to complete the study. Those who stayed in the study completed 98.7% of the cycle training sessions.

A major limitation of the study was the short 6-wk duration of training. For highly-trained runners, it is likely that more time training with the PowerCranks™ is required to realize an improvement. However, as the subjects (i.e., athletes) progressed with their track and field season, they and their coaches were unwilling to extend the study. Also, the testing of running economy was limited to when the subjects were well rested. The post-training effect from PowerCranks™ on running economy when athletes are fatigued is unknown and, therefore, is an area for future research.
The most difficult part of a study is not in the data collection but in the interpretation of the results. It is equally important to examine why a study might have failed to show a difference as it is to note that it did fail to show a difference. Most of the negative cycling studies have similar deficiencies to this study but these were not commented on by the authors to the same extent. I suspect the difference lies in the fact that Wagner, et al. knew from previous studies that HF's were important to running and expected a positive result and were trying to explain why they didn't see it whereas most cycling researchers do not believe HF's or technique to be important to cycling so found no need to try to explain a negative result, even though others have seen positive results.
 
FrankDay said:
It is more difficult to improve economy of motion in highly skilled athletes than novices

Again, this is stating the obvious and is the main reason why we should test with trained athletes so we don't delude ourselves. The main failing of most sport science studies is that they use untrained or poorly trained subjects and the performance changes in no way reflect the responses and adaptations you would expect from a well trained or elite subject.
 
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CoachFergie said:
Originally Posted by FrankDay
It is more difficult to improve economy of motion in highly skilled athletes than novices
Again, this is stating the obvious and is the main reason why we should test with trained athletes so we don't delude ourselves. The main failing of most sport science studies is that they use untrained or poorly trained subjects and the performance changes in no way reflect the responses and adaptations you would expect from a well trained or elite subject.
I guess you can take that point but most researchers are interested in getting positive results. Since it is easier to get results in the lesser trained it seems to me, if I wanted to prove a concept that I would start there. Once we understand that the concept works then one can test to see what is required to get results in the highly trained. So, we know from Luttrell that 6 weeks of part-time use can result in demonstrable benefits in the not very well trained but active cyclist but that similar intervention doesn't work in that period of time in more elite cyclists. That is not proof that the concept doesn't work but only that was not enough intervention to demonstrate improvement in highly trained cyclists. But, Dixon was able to demonstrate that 6 weeks is enough time to demonstrate improvement in highly trained cyclists if an immersion intervention is used.

So, there is stuff to be learned from those negative studies. It just isn't what you think it is.
 
FrankDay said:
I guess you can take that point but most researchers are interested in getting positive results.

Exercise physiologists will look for any improvement but a sport scientist will look for performance gains at the highest level possible.

Since it is easier to get results in the lesser trained it seems to me, if I wanted to prove a concept that I would start there.

If you wanted to delude yourself over the potential of anything.

Once we understand that the concept works then one can test to see what is required to get results in the highly trained.

A lazy approach.

So, we know from Luttrell that 6 weeks of part-time use can result in demonstrable benefits in the not very well trained but active cyclist but that similar intervention doesn't work in that period of time in more elite cyclists.

No change in IAT in the experimental group. This was the only test of cycling fitness they performed.

That is not proof that the concept doesn't work but only that was not enough intervention to demonstrate improvement in highly trained cyclists.

Where other interventions show a positive adaptation is not only possible in a matter of days but after 5-6 weeks the performance gains start to taper off.

But, Dixon was able to demonstrate that 6 weeks is enough time to demonstrate improvement in highly trained cyclists if an immersion intervention is used.

No details available about whether they were highly trained. Their VO2max scores would suggest otherwise. And of course no control group. Need to compare with a control group using normal cranks and a matched workload.
 
CoachFergie said:
The Impact of 10 weeks of Independent Cycle Crank use on
Cycle Performance
Robert M. Otto, FACSM, Laura Walsh, Jessica Marra, Christopher
Kushner, Alicia Diaz, Carolyn Richardson, John W. Wygand.
Adelphi University, Garden City, NY.
Email: otto@adelphi.edu
(No relationships reported)
Improvements in cycle performance may be a result of enhanced efficiency and/or a greater
power output. Cyclists strive to achieve both by over-distance training, high intensity
training, and specific cycle drills. Special products that claim to improve performance
by offering improved aerodynamics, reduced total cycle mass, better force transfer to the
crank, or providing biomechanical feedback rely on a paucity of research.
PURPOSE: To evaluate the effect of ten weeks of using independent cycle cranks
(ICC) on cycling performance as measured by oxygen efficiency (OxE), time trial
performance (TT), and body composition (BC).
METHODS: After a medical/health screening, thirty triathletes (16 male, 14 female)
(age 43.2 [range 25-54 yr], ht 176 [range 160-188 cm], and body mass 73.3 [range
54.3-97.7.5 kg]), participated in familiarization trials including DEXA scan, electronic
cycle ergometer based steady state OxE trial and a time trial. Identical testing was
performed during the familiarization trial, pre-test (within one week) and the posttest
(ten weeks later). After the pre-test trial, subjects were randomly assigned to one
of three groups (C = control, 90 = 90 min/wk and 180 = min/wk). For ten weeks all
subjects exercised (swim, cycle, run) a minimum of eight hours per week. All groups
cycled a minimum of three hours/week with C in fixed cranks, 90 for 90 min fixed and
90 min ICC, and 180 for 180 min ICC.
RESULTS: Statistical analysis by ANOVA (P<.05) reveals no significant difference among or
between trials.
CONCLUSION: The use of independent cycle crank arms for a maximum of 30 hours
within ten weeks, requires the user to apply force independent of crank position, but
does not result in quantifiable changes in cycle efficiency or performance

This study bears repeating as it was carried out over 10 weeks. Still no improvement in performance.
 
From Jobson (2012)

Therefore, the question arises as to whether or not changes in pedalling technique can affect cycling efficiency if participants are given the opportunity to adapt to a new pedalling style. To address this question, several authors have used the decoupled crank paradigm to investigate the issue longitudinally. Training with decoupled cranks forces the cyclist to actively pull on the pedal during the upstroke, with potential implications for pedalling technique and cycling efficiency. Luttrell & Potteiger (2003) reported that 6 weeks of training with decoupled cranks resulted in improved cycling efficiency. However, the participant selection in this study was poorly controlled, and thus, the meaningfulness of these results is limited. Williams et al. (2009) quantified the effect of training with decoupled cranks on pedalling technique and cycling efficiency in a more controlled fashion. These authors found no significant effects of training with decoupled cranks on cycling efficiency. Expanding on these results, Böhm et al. (2008) showed that training with decoupled cranks can change certain aspects of the pedalling technique without changing physiological variables. Together, the experimental evidence suggests that the acquisition of new pedalling techniques does not result in significant increases in gross efficiency in the short to medium term.
 

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