Prior muscular exercise affects cycling pattern (original) (raw)
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Acta Physiologica Hungarica, 2014
The effect of cycling cadence and crank resistance on the activity of hamstrings and quadriceps muscles was investigated during cycling movements of able-bodied subjects on a stationary bike with slow and fast speed against different resistance conditions. The ratio of average EMG amplitudes obtained in the two speed conditions (fast/ slow) was computed in each resistance condition. This ratio is higher for both muscles if cycling against higher resistance. This shows that in higher resistance condition muscle activities are not only increased but the change of muscle activities with respect to cadence change varied according to resistance condition. Average EMG amplitudes increased at a higher rate with respect to change of cadence when cycling was performed in higher resistance condition. Besides, when cycling faster, hamstrings activity increased generally at a higher rate than that of quadriceps. The correlation between cadence and EMG amplitudes were also investigated. Considering hamstrings, this correlation was low and decreased as resistance increased. The correlation between the time required to drive one cycle and EMG amplitude is negative but in absolute value it is larger than the correlation of cadence and EMG amplitude.
Effects of Eccentric Exercise on Cycling Efficiency
Canadian Journal of Applied Physiology, 2005
The aim of this study was to find out whether the efficiency of concentric muscle contraction is impaired by eccentric squatting exercise. The study involved 25 male physical education students in two experiments. In the first experiment 14 subjects undertook cycling exercise at 65% [Formula: see text]max until exhaustion on two occasions. During the experimental condition their cycling was interrupted every 10 min so they could perform eccentric squatting exercise, whereas in the control condition they rested seated on the bike during the interruptions. Eccentric squatting consisted of 10 series of 25 reps with a load equivalent to 150% of the subject's body mass on the shoulders. During the first experiment gross efficiency decreased (mean ± SE) from 17.1 ± 0.3 to 16.0 ± 0.4%, and from 17.2 ± 0.3 to 16.5 ± 0.4%, between the 2nd and 9th cycling bouts of the experimental and control conditions, respectively (both p
Journal of Electromyography and Kinesiology, 2010
Purpose: This study investigated the effects of a combined endurance and strength training on the physiological and neuromuscular parameters during a 2-h cycling test. Methods: Fourteen triathletes were assigned to an endurance-strength training group and an enduranceonly training group. They performed three experimental trials before and after training: an incremental cycling test to exhaustion, a maximal concentric lower-limbs strength measurement and a 2-h cycling exercise. Physiological parameters, free cycling chosen cadence and the EMG of Vastus Lateralis (VL) and Rectus Femoris (RF) were analysed during the 2-h cycling task before and after a strength training programme of 5 weeks (three times per week).
Muscle activation during cycling at different cadences: Effect of maximal strength capacity
Journal of Electromyography and Kinesiology, 2007
The purpose of this study was to examine the influence of maximal strength capacity on muscle activation, during cycling, at three selected cadences: a low cadence (50 rpm), a high cadence (110 rpm) and the freely chosen cadence (FCC). Two groups of trained cyclists were selected on the basis of the different maximal isokinetic voluntary contraction values (MVCi) of their lower extremity muscles as follow: Fmin (lower MVCi group) and Fmax (higher MVCi group). All subjects performed three 4-min cycling exercises at a power output corresponding to 80 % of the ventilatory threshold under the three cadences. Neuromuscular activity of vastus lateralis (VL), rectus femoris (RF) and biceps femoris (BF) was studied quantitatively (integrated electromyography, IEMG) and qualitatively (timing of muscle bursts during crank cycle). Cadence effects were observed on the EMG activity of VL muscle and on the burst onset of the BF, VL and RF muscles. A greater normalized EMG activity of VL muscle was observed for the Fmin group than the Fmax group at all cadences (respectively Fmin vs. Fmax at 50 rpm: 17% ± 5 vs. 38% ± 6, FCC: 22% ± 7 vs. 44% ± 5 and 110 rpm: 21% ± 6 vs. 45% ± 6). At FCC and 110 rpm, the burst onset of BF and RF muscles of the Fmax group started earlier in the crank cycle than the Fmin group These results indicate that in addition to the cadence, the maximal strength capacity influences the lower extremity muscular activity during cycling.
Effect of pedaling technique on muscle activity and cycling efficiency
European Journal of Applied Physiology, 2007
The purpose of this study was to examine the acute effect of talocrural joint position on muscle activity and gross mechanical efficiency (GE). Eleven trained cyclists participated in three randomized 6-min cycling bouts at~80% of maximal aerobic capacity on an electromagnetically braked cycle ergometer while oxygen consumption and muscle activity (EMG) were monitored during the subject's self-selected pedaling technique (control) and while using a dorsi-and plantarflexed pedaling technique. The mean differences in range of motion of the dorsi-and plantarflexed technique from the control position were 7.1 ± 4.4 and 6.9 ± 5.4°, respectively. Gastrocnemius EMG activity was higher with the dorsiflexion technique than when using the self-selected control position (33.2 ± 13.0 and 24.2 ± 8.4 lV s, respectively; P < 0.05). Moreover, GE was 2.6% lower while riding with the dorsiflexion technique than the control position (19.0 ± 1.2 and 19.5 ± 1.3%, respectively; P < 0.05). The data suggested that introducing more dorsiflexion into the pedal stroke of a trained cyclist increases muscle activity of the gastrocnemius lateralis and decreased GE when compared to the self-selected pedal stroke.
Journal of NeuroEngineering and Rehabilitation, 2014
Background: A better understanding of lower-extremity muscles' activation patterns and joint kinematics during different workloads could help rehabilitation professionals with prescribing more effective exercise regimen for elderly and those with compromised muscles. We examined the relative contribution, as well as activation and co-activation patterns, of lower-extremity muscles during semi-reclined cycling at different workloads during a constant cadence. Methods: Fifteen healthy novice cyclists participated at three 90-second cycling trials with randomly assigned workloads of 0, 50, and 100 W, at a constant cadence of 60 rpm. During all trials, electromyograms were recorded from four lower-extremity muscles: rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius medialis (GT). Joint kinematics were also recorded and synchronized with the EMG data. Muscle burst onset, offset, duration of activity, peak magnitude, and peak timing, as well as mean joint angles and mean ranges of motion were extracted from the recorded data and compared across workloads. Results: As workload increased, BF and TA displayed earlier activations and delayed deactivations in each cycle that resulted in a significantly (p < 0.05) longer duration of activity at higher workloads. RF showed a significantly longer duration of activity between 0 and 50 W as well as 0 and 100 W (p < 0.05); however, the activity duration of GT was not appeared to be affected significantly by workload. EMG peak-magnitude of RF, BF, and TA changed significantly (p < 0.05) as workload increased, but no changes were observed in the EMG peak-timing across workloads. Durations of co-activation in the RF-BF pair as well as the RF-TA pair increased significantly with workload, while the RF-TA and TA-GT pairs were only significantly different (p < 0.05) between the 0 and 100 W workload levels. Increased workload did not lead to any significant changes in the joint kinematics.
Evidence of neuromuscular fatigue after prolonged cycling exercise
Medicine & Science …, 2000
The purpose of this study was to analyze the effects of prolonged cycling exercise on metabolic, neuromuscular, and biomechanical parameters. Methods: Eight well-trained male cyclists or triathletes performed a 2-h cycling exercise at a power output corresponding to 65% of their maximal aerobic power. Maximal concentric (CON; 60, 120, 240°⅐s Ϫ1), isometric (ISO; 0°⅐s Ϫ1), and eccentric (ECC; Ϫ120,-60°⅐s Ϫ1) contractions, electromyographic (EMG) activity of vastus lateralis (VL) and vastus medialis (VM) muscles were recorded before and after the exercise. Neural (M-wave) and contractile (isometric muscular twitch) parameters of quadriceps muscle were also analyzed using electrical stimulation techniques. Results: Oxygen uptake (V O 2), minute ventilation (V E), and heart rate (HR) significantly increased (P Ͻ 0.01) during the 2-h by, respectively, 9.6%, 17.7%, and 12.7%, whereas pedaling rate significantly decreased (P Ͻ 0.01) by 21% (from 87 to 69 rpm). Reductions in muscular peak torque were quite similar during CON, ISO, and ECC contractions, ranging from 11 to 15%. M-wave duration significantly increased (P Ͻ 0.05) postexercise in both VL and VM, whereas maximal amplitude and total area decreased (VM: P Ͻ 0.05, VL: NS). Significant decreases in maximal twitch tension (P Ͻ 0.01), total area of mechanical response (P Ͻ 0.01), and maximal rate of twitch tension development (P Ͻ 0.05) were found postexercise. Conclusions: A reduction in leg muscular capacity after prolonged cycling exercise resulted from both reduced neural input to the muscles and a failure of peripheral contractile mechanisms. Several hypothesis are proposed to explain a decrease in pedaling rate during the 2-h cycling with a constancy of power output and an increase in energy cost.
Lower limb muscle activation during a 40km cycling time trial: Co-activation and pedalling technique
2011
Background: Knee extensors muscle activation could be optimized by a reduced activation of knee joint flexor muscles (co-activation) during fatigue. Time trial events are based on the management of energy resources by controlling muscle activation by focusing on optimizing performance and avoiding premature fatigue. Research question: Is there a reduction on muscle co-activation and variability of muscle activity during the recovery phase of pedal cycle which could influence pedalling technique and time trial performance? Type of study: Cross-sectional. Methods: Subjects: Eight triathletes. Experimental procedure: Maximal oxygen uptake and power output evaluation session. Cycling time trial performance session with the measurement of muscle activity by means of electromyography. Outcome measurements: Knee and ankle muscle co-activation, muscle activation variability, and muscle activation during the recovery phase of a pedal cycle. Results: Increased variability of biceps femoris and increased recruitment of vastus lateralis at the end of the time trial. No differences found for muscle co-activation. Conclusion: Individual strategies regarding biceps femoris activation are suggested based on changes in muscle activation variability. Vastus lateralis showed increased activation during the recovery phase, probably as an attempt to improve power output in the propulsion phase.