Heliox increases lower limb O(2)DEL and utilization during dynamic exercise in patients with moderate to severe COPD. These effects enhance exercise tolerance in this patient population.

LEDT treatment produced a smaller maximal isometric torque decrease after high-intensity concentric isokinetic exercise, which is consistent with an increase in performance.

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Muscle fatigue may alter kinematics and contribute to repetitive strain injuries. This study quantified how both localized muscle fatigue and movement kinematics change over time during exhaustive cycling. Seven highly trained cyclists rode a stationary bicycle ergometer at 100% of their VO 2 max until voluntary exhaustion. Cycling kinematics and EMG activity from select lower extremity muscles were recorded. Cross-correlations were computed to quantify how EMG median frequencies (MDF) changed with changes in movement kinematics. All athletes maintained both cadence and power output for ~90% of the trial duration. Significant sustained muscle fatigue occurred in 18 of 28 muscles tested, most prominently in the biceps femoris (p = 0.020) and gastrocnemius (p = 0.018). Kinematics and MDF both fluctuated non-monotonically as subjects fatigued. Changes in MDF significantly preceded changes in mean trunk lean (p = 0.009) and hip angles (p = 0.025), and trunk lean range of motion (p = 0.029). Fluctuations in MDF were positively correlated with fluctuations in mean trunk lean (p = 0.009) and knee splay angles (p = 0.011), and with trunk lean (p = 0.002) and ankle (p = 0.001) range of motion. These results therefore establish a direct link between changes in muscle fatigue state and subsequent changes in movement kinematics during cycling..

This study investigated the effects of changing cadence and workload on pedaling technique. Eight cyclists were evaluated during an incremental maximal cycling and two 30-minute submaximal trials at 60% and 80% of maximal power output (W(60%) and W(80%), respectively). During submaximal 30-minute trials, they cycled for 10 minutes at a freely chosen cadence (FCC), 10 minutes at a cadence 20% above FCC (FCC+20%), and 10 minutes at a cadence 20% below FCC (FCC-20%). Pedal forces and kinematics were evaluated. The resultant force (RF), effective force (EF), index of effectiveness (IE) and IE during propulsive and recovery phase (IEprop and IErec, respectively) were computed. For W(60%), FCC-20% and FCC presented higher EFmean (69+/-9 N and 66+/-14 N, respectively) than FCC+20% (52+/-14 N). FCC presented the highest IEprop (81+/-4%) among the cadences (74+/-4 and 78+/-5% for FCC-20% and FCC+20%, respectively). For W(80%), FCC presented higher EFmean (81+/-5 N) than FCC+20% (72 +/- 10 N). The FCC-20% presented the lower IEprop (71+/-7%) among the cadences. The EFmin was higher for W(80%) than W(60%) for all cadences. The IE was higher at W (80%) (61+/-5%) than W (60%) (54+/-9%) for FCC+20% (all p<0.05). Lower cadences were more effective during the recovery phase for both intensities and FCC was the best technique during the propulsive phase.

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Reaction time and response time are considered important abilities and can potentially affect combat performance. This study investigated the effect of a specific fatigue protocol on reaction time, response time, performance time, and kick impact. Seven male athletes reported to the laboratory on two different days. During day one, athletes performed a specific progressive taekwondo test, and on day two, a protocol for determining reaction time, response time, performance time, and kick impact before and after a time to exhaustion test at an intensity level corresponding to the maximal kick frequency obtained during the specific progressive taekwondo test. Muscle activation from rectus femoris and kick impact of the preferred limb were assessed. No differences were observed for response time and performance time. However, kick impact decreased (43 ± 27 to 13 ± 10 g, p < 0.01) while reaction time increased (145 ± 51 to 223 ± 133 ms, p < 0.05). Moderate correlation was observed between kick impact and response time (r = 0.565; p < 0.01), and kick impact and performance time (r = 0.494; p < 0.05). Results indicate that coaches and athletes may use taekwondo training programmes on coordination-based exercises leading to improve response time and to reduce fatigue effects in order to improve technique effectiveness and enhance the possibilities of scoring in a competitive situation.