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Altered muscle coordination when pedaling with independent cranks.

Hug F, Boumier F, Dorel S - Front Physiol (2013)

Bottom Line: When the mean EMG activity across the cycle was considered, the use of independent cranks significantly increased the activity level compared to control for Tibialis anterior (TA) (P = 0.0017; +336 ± 302%), Gastrocnemius medialis (GM) (P = 0.0005; +47 ± 25%), Rectus femoris (RF) (P = 0.005; +123 ± 153%), Biceps femoris (BF)-long head (P = 0.0001; +162 ± 97%), Semimembranosus (SM) (P = 0.0001; +304 ± 192%), and Tensor fascia latae (P = 0.0001; +586 ± 262%).In addition, a high inter-individual variability was found in the way the participants adapted to pedaling with independent cranks.The present results showed that the enforced pull-up action required when using independent cranks was achieved by increasing the activation of hip and knee flexors.

View Article: PubMed Central - PubMed

Affiliation: Laboratory "Motricité, Interactions, Performance" (EA 4334), UFR STAPS, University of Nantes Nantes, France ; NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, The University of Queensland Brisbane, QLD, Australia.

ABSTRACT
Pedaling with independent cranks ensures each leg cycles independently of the other, and thus eliminates the contribution of the contralateral leg during the upstroke phase. Consequently the subject is required to actively pull-up the pedal to complete the cycle. The present study aimed to determine the acute effect of the use of independent cranks on muscle coordination during a submaximal pedaling exercise. Ten healthy males were asked to perform submaximal pedaling exercises at 100 Watts with normal fixed cranks (control condition) or independent cranks. Both 2-D pedal forces and electromyographic (EMG) SIGNALS of 10 lower limb muscles were recorded. When the mean EMG activity across the cycle was considered, the use of independent cranks significantly increased the activity level compared to control for Tibialis anterior (TA) (P = 0.0017; +336 ± 302%), Gastrocnemius medialis (GM) (P = 0.0005; +47 ± 25%), Rectus femoris (RF) (P = 0.005; +123 ± 153%), Biceps femoris (BF)-long head (P = 0.0001; +162 ± 97%), Semimembranosus (SM) (P = 0.0001; +304 ± 192%), and Tensor fascia latae (P = 0.0001; +586 ± 262%). The analysis of the four pedaling sectors revealed that the increased activity of hip and knee flexors mainly occurred during the top dead center and the upstroke phase. In addition, a high inter-individual variability was found in the way the participants adapted to pedaling with independent cranks. The present results showed that the enforced pull-up action required when using independent cranks was achieved by increasing the activation of hip and knee flexors. Further studies are needed to determine whether training with independent cranks has the potential to induce long-term changes in muscle coordination, and, if so, whether these changes are beneficial for cycling performance.

No MeSH data available.


Related in: MedlinePlus

Change in ensemble-averaged EMG patterns. EMG patterns were averaged across 30 consecutive pedaling cycles and expressed as a function of the left crank angle as it rotated from the highest pedal position (0°) to the lowest pedal position (180°) and back to the highest position. To compare the shape of the EMG patterns, the amplitude was first normalized for each condition by the average of its peak from all cycles (panel A). To compare both the shape and the amplitude of the EMG patterns, the amplitude was then normalized by the average of its peak from all cycles measured during the control condition (panel B). TA, tibialis anterior; SOL, soleus; GL, gastrocnemius lateralis; GM, gastrocnemius medialis; VL, vastus lateralis; RF, rectus femoris; VM, vastus medialis; BF, long head of biceps femoris; SM, semimembranosus; TF, tensor fascia latae.
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Figure 2: Change in ensemble-averaged EMG patterns. EMG patterns were averaged across 30 consecutive pedaling cycles and expressed as a function of the left crank angle as it rotated from the highest pedal position (0°) to the lowest pedal position (180°) and back to the highest position. To compare the shape of the EMG patterns, the amplitude was first normalized for each condition by the average of its peak from all cycles (panel A). To compare both the shape and the amplitude of the EMG patterns, the amplitude was then normalized by the average of its peak from all cycles measured during the control condition (panel B). TA, tibialis anterior; SOL, soleus; GL, gastrocnemius lateralis; GM, gastrocnemius medialis; VL, vastus lateralis; RF, rectus femoris; VM, vastus medialis; BF, long head of biceps femoris; SM, semimembranosus; TF, tensor fascia latae.

Mentions: For each condition, the normalized EMG patterns for the 10 muscles investigated are shown in Figure 2. Overall, EMG patterns of the Control condition were similar to those already reported in the literature (for a review, see Hug and Dorel, 2009). When the shape of the EMG patterns is considered (patterns normalized for each condition to the average of the peaks amplitude; Figure 2A), it appears that some muscles were more affected by the use of independent cranks (e.g., TA, BF, SM, and TF). Note that TA, BF and SM were active during a longer period of the cycle when pedaling with independent cranks compared to Control (Figure 2A). When patterns normalized to the average of the peaks amplitude of the Control condition are considered (Figure 2B), it clearly appears that the magnitude of activation of some muscles was greatly altered by the use of independent cranks, as quantified below.


Altered muscle coordination when pedaling with independent cranks.

Hug F, Boumier F, Dorel S - Front Physiol (2013)

Change in ensemble-averaged EMG patterns. EMG patterns were averaged across 30 consecutive pedaling cycles and expressed as a function of the left crank angle as it rotated from the highest pedal position (0°) to the lowest pedal position (180°) and back to the highest position. To compare the shape of the EMG patterns, the amplitude was first normalized for each condition by the average of its peak from all cycles (panel A). To compare both the shape and the amplitude of the EMG patterns, the amplitude was then normalized by the average of its peak from all cycles measured during the control condition (panel B). TA, tibialis anterior; SOL, soleus; GL, gastrocnemius lateralis; GM, gastrocnemius medialis; VL, vastus lateralis; RF, rectus femoris; VM, vastus medialis; BF, long head of biceps femoris; SM, semimembranosus; TF, tensor fascia latae.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3755179&req=5

Figure 2: Change in ensemble-averaged EMG patterns. EMG patterns were averaged across 30 consecutive pedaling cycles and expressed as a function of the left crank angle as it rotated from the highest pedal position (0°) to the lowest pedal position (180°) and back to the highest position. To compare the shape of the EMG patterns, the amplitude was first normalized for each condition by the average of its peak from all cycles (panel A). To compare both the shape and the amplitude of the EMG patterns, the amplitude was then normalized by the average of its peak from all cycles measured during the control condition (panel B). TA, tibialis anterior; SOL, soleus; GL, gastrocnemius lateralis; GM, gastrocnemius medialis; VL, vastus lateralis; RF, rectus femoris; VM, vastus medialis; BF, long head of biceps femoris; SM, semimembranosus; TF, tensor fascia latae.
Mentions: For each condition, the normalized EMG patterns for the 10 muscles investigated are shown in Figure 2. Overall, EMG patterns of the Control condition were similar to those already reported in the literature (for a review, see Hug and Dorel, 2009). When the shape of the EMG patterns is considered (patterns normalized for each condition to the average of the peaks amplitude; Figure 2A), it appears that some muscles were more affected by the use of independent cranks (e.g., TA, BF, SM, and TF). Note that TA, BF and SM were active during a longer period of the cycle when pedaling with independent cranks compared to Control (Figure 2A). When patterns normalized to the average of the peaks amplitude of the Control condition are considered (Figure 2B), it clearly appears that the magnitude of activation of some muscles was greatly altered by the use of independent cranks, as quantified below.

Bottom Line: When the mean EMG activity across the cycle was considered, the use of independent cranks significantly increased the activity level compared to control for Tibialis anterior (TA) (P = 0.0017; +336 ± 302%), Gastrocnemius medialis (GM) (P = 0.0005; +47 ± 25%), Rectus femoris (RF) (P = 0.005; +123 ± 153%), Biceps femoris (BF)-long head (P = 0.0001; +162 ± 97%), Semimembranosus (SM) (P = 0.0001; +304 ± 192%), and Tensor fascia latae (P = 0.0001; +586 ± 262%).In addition, a high inter-individual variability was found in the way the participants adapted to pedaling with independent cranks.The present results showed that the enforced pull-up action required when using independent cranks was achieved by increasing the activation of hip and knee flexors.

View Article: PubMed Central - PubMed

Affiliation: Laboratory "Motricité, Interactions, Performance" (EA 4334), UFR STAPS, University of Nantes Nantes, France ; NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, The University of Queensland Brisbane, QLD, Australia.

ABSTRACT
Pedaling with independent cranks ensures each leg cycles independently of the other, and thus eliminates the contribution of the contralateral leg during the upstroke phase. Consequently the subject is required to actively pull-up the pedal to complete the cycle. The present study aimed to determine the acute effect of the use of independent cranks on muscle coordination during a submaximal pedaling exercise. Ten healthy males were asked to perform submaximal pedaling exercises at 100 Watts with normal fixed cranks (control condition) or independent cranks. Both 2-D pedal forces and electromyographic (EMG) SIGNALS of 10 lower limb muscles were recorded. When the mean EMG activity across the cycle was considered, the use of independent cranks significantly increased the activity level compared to control for Tibialis anterior (TA) (P = 0.0017; +336 ± 302%), Gastrocnemius medialis (GM) (P = 0.0005; +47 ± 25%), Rectus femoris (RF) (P = 0.005; +123 ± 153%), Biceps femoris (BF)-long head (P = 0.0001; +162 ± 97%), Semimembranosus (SM) (P = 0.0001; +304 ± 192%), and Tensor fascia latae (P = 0.0001; +586 ± 262%). The analysis of the four pedaling sectors revealed that the increased activity of hip and knee flexors mainly occurred during the top dead center and the upstroke phase. In addition, a high inter-individual variability was found in the way the participants adapted to pedaling with independent cranks. The present results showed that the enforced pull-up action required when using independent cranks was achieved by increasing the activation of hip and knee flexors. Further studies are needed to determine whether training with independent cranks has the potential to induce long-term changes in muscle coordination, and, if so, whether these changes are beneficial for cycling performance.

No MeSH data available.


Related in: MedlinePlus