Knee peak torque (PT) is associated to jump performance in volleyball players. It is not clear whether muscle strength imbalances of the knee joint can influence jump performance. The purpose of study was to analyse the association between PT and knee muscular imbalances with jump performance in professional volleyball players. Eleven elite male volleyball players (90.3 ± 9.7 kg body mass and 1.94 ± 0.06 m height) were evaluated in an isokinetic dynamometer at speeds of 60, 180 and 300 deg/s. Muscle strength imbalances were obtained through calculation of contralateral deficit between limbs and the conventional ratio (hamstrings/quadriceps). Countermovement jump (CMJ) was performed on a force plate to calculate mechanical power and height. Association was found between knee extensor PT at 180 deg/s with CMJ power (r = 0.610, p = 0.046). Conventional ratio at 300 deg/s showed negative association with CMJ (r = −0.656, p = 0.029). The optimal ratio between knee extensors PT in relation to the flexors PT is associated with the greater mechanical power in CMJ. Contralateral deficit does not seem to be associated with the CMJ performance. Considering the knee extensor PT is associated with CMJ power, our findings suggest that strength-based training in volleyball athletes should not omit the conventional muscle ratio.

To investigate the impact of respiratory muscle endurance training (RMET) on lung function and exercise performance in athletes with high lesion level paraplegia. This was a case-control intervention study. Sport and exercise science laboratories and bike path. Twelve competitive handbike athletes with high lesion level paraplegia matched by lesion and fitness level in training (T) group (7) and control (C) group (5). The T group performed 20 RMET training sessions over a 4-week period using a SpiroTiger. Each session lasted for 30 minutes. The C group did not perform any RMET. Resting lung function, respiratory muscle endurance, and exercise performance (arm cranking maximal incremental test and simulated handbike time trial). Resting lung function was not different between groups and did not change with the intervention. After RMET, the respiratory muscle endurance was significantly increased by 27% in the T group but did not alter in the C group. Final minute ventilation was increased from 89 ± 20 L/min to 112 ± 20 L/min after RMET in the T group and the sensation of dyspnea decreased (P < 0.05). Peak oxygen consumption, peak mechanical power output, and handbike time trial performance were not different between groups and did not change with the RMET intervention. A short-term RMET intervention in handbike athletes with high lesion level paraplegia improved respiratory muscle endurance but had little impact on overall exercise performance.

Purpose: To investigate physiological performance determinants of the partial laps and an overall 22-km handbiking (HB) time trial in athletes with high paraplegia.Methods: Seven male HB athletes with spinal cord injury (lesion levels thoracic 2-8) performed a laboratory maximal incremental test under cardiorespiratory-mechanical monitoring including respiratory-exchange ratio (RER), oxygen uptake (V̇O₂), and mechanical power output (PO). Individual first and second ventilatory thresholds (V̇O_2VT1 and V̇O_2VT2), V̇O_2peak, and PO_peak were posteriorly identified. Athletes also performed a simulated HB time trial along a 4-lap bike circuit under cardiorespiratory measurement. Overall metabolic cost (C) and %V̇O_2peak (ratio of V̇O₂ to V̇O_2peak) were calculated from race data. Race performance was defined as mean race velocity (v).Results: athletes completed the 22-km HB time trial in 45 ± 6 min, at 29.9 ± 3.6 km/h, with %V̇O_2peak = 0.86 ± 0.10 and RER = 1.07 ± 0.17. V̇O_2peak (r = .89, P = .01), PO_peak (r = .85, P = .02), V̇O_2VT1 (r = .96, P = .001), V̇O_2VT2 (r = .92, P = .003), and C (2nd lap, r = .78; 3rd lap, r = .80; and 4th lap, r = .80) were significantly (P < .05) positively correlated with race performance. Within-subjects correlation coefficient revealed a large and significant (r = .68, P < .001) relationship between %V̇O_2peak and v.Conclusions: V̇O_2peak, PO_peak, ventilatory thresholds, %V̇O_2peak, and C appeared to be important physiological performance determinants of HB time trial.

Despite the evolution of runner performance in athletes with cerebral palsy (CP), little is known about neuromuscular parameters of sprinters from different classes, especially related to power output, muscular imbalances and asymmetry indexes in lower limbs. The aim of this study was to assess muscle power, muscular imbalance and asymmetry in sprinters with CP. Four male sprinters with CP (age, 18 to 27 years; body mass, 58.5 to 72.8 kg; height, 161.5 to 174 cm) classified as T38, T37, T36, T35 according to International Paralympic Committee functional classification, performed vertical counter movement jump and squat jump on force plate and isokinetic torque evaluations in both limbs. The concentric peak torque (PT) was measured at 60°/sec, 120°/sec and 180°/sec and PT eccentric at 60°/sec and 120°/sec. The asymmetry indexes, conventional and functional ratios were assessed. the results showed that athletes with more severe impairments (T35 and T36) showed worse performance to muscle power, more muscular imbalance and higher asymmetry in PT between limbs (> 10%). The exception was T37 athlete, who presented the better performance for all variables. it is concluded that CP athletes with more severe impairments showed lower jumping performance and torque production of knee extensors and flexors, they showed greater asymmetries between limbs. Finally, considering the results of T37 athlete, it seems that the athletic training for a longer period can reverse part of the neuromuscular impairments caused by CP.

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