ABSTRACT
The aim of this study was to examine absolute and relative reliability of fatigue measures calculated from peak torque or total work during 20, 30, 40 and 50 reciprocal maximal concentric contractions performed on an isokinetic dynamometer at 180 degrees x s(-1). Eighteen moderately active men performed 50 reciprocal maximal concentric contractions on three occasions with one 7-10 days recovery between each session. Peak torque and total work were computed for each contraction and subsequently summed to compute cumulated performance after respectively 20, 30, 40 and 50 repetitions. Muscle fatigue was determined after 20, 30, 40 and 50 repetitions by the fatigue index, the percent decrease in performance and the slope. Reliability of average peak torque or average total work was similar and was not affected by the lengthening of the protocol, although a learning effect was evident for knee flexors. Reliability of fatigue measures calculated from peak torque or total work was similar, improved with the lengthening of the protocol and was better for knee extensors. Measuring average peak torque or average total work and the slope during a protocol involving 30 maximal reciprocal concentric contractions appear to represent a better compromise between reliability and physiological interpretability of the data.
Subject(s)
Exercise , Muscle Fatigue/physiology , Muscle, Skeletal/physiology , Adult , Humans , Knee/physiology , Male , Physical Endurance , Torque , Young AdultABSTRACT
Muscle strength and anaerobic power of the lower extremities are neuromuscular variables that influence performance in many sports activities, including soccer. Despite frequent contradictions in the literature, it may be assumed that muscle strength and balance play a key role in targeted acute muscle injuries. The purpose of the present study was to provide and compare pre-season muscular strength and power profiles in professional and junior elite soccer players throughout the developmental years of 15-21. One original aspect of our study was that isokinetic data were considered alongside the past history of injury in these players. Fifty-seven elite and junior elite male soccer players were assigned to three groups: PRO, n=19; U-21, n=20 and U-17, n=18. Players benefited from knee flexor and extensor isokinetic testing consisting of concentric and eccentric exercises. A context of lingering muscle disorder was defined using statistically selected cut-offs. Functional performance was evaluated throughout a squat jump and 10 m sprint. The PRO group ran faster and jumped higher than the U-17 group (P<0.05). No significant difference in isokinetic muscle strength performance was observed between the three groups when considering normalized body mass parameters. Individual isokinetic profiles enabled the identification of 32/57 (56%) subjects presenting lower limb muscular imbalance. Thirty-six out of 57 players were identified as having sustained a previous major lower limb injury. Of these 36 players, 23 still showed significant muscular imbalance (64%). New trends in rational training could focus more on the risk of imbalance and implement antagonist strengthening aimed at injury prevention. Such an intervention would benefit not only athletes recovering from injury, but also uninjured players. An interdisciplinary approach involving trainers, a physical coach, and medical staff would be of interest to consider in implementing a prevention programme.
Subject(s)
Athletic Injuries/etiology , Athletic Performance/physiology , Muscle Strength/physiology , Soccer/injuries , Adolescent , Adult , Belgium , Exercise Test , Humans , Male , Risk Assessment , Young AdultABSTRACT
Maximal oxygen uptake (VO2 max) is regarded by some as the best single measurement of aerobic fitness. An other major determinant of successful endurance performance is the percentage of VO2 max that an athlete can maintain for a prolonged period. It is related to the lactate threshold. Two other factors also appear to be important for endurance activities as high economy of effort, or low VO2 value for the same rate of work; high percentage of ST muscle fibers. In the laboratory, the usual measurements of aerobic power include the determination of maximum oxygen consumption and the identification of lactate threshold. Testing aerobic power can help determine the type of aerobic training that should be emphasized.
Subject(s)
Athletic Performance/physiology , Oxygen Consumption , Exercise/physiology , Humans , Lactic Acid/metabolism , Physical Fitness/physiologyABSTRACT
As for other skeletal muscles, ventilatory muscle performance can be described in terms of strength and endurance. Ventilatory muscle strength is measured, for example, as the maximum inspiratory and expiratory mouth pressures. It is now a routine procedure in many pulmonary function laboratories. Measurements of ventilatory muscle endurance are more difficult but two general types of tests are used: maximum voluntary ventilation and inspiratory threshold loading.
