Muscle fatigue experienced during maximal eccentric exercise is predictive of the plasma creatine kinase (CK) response

in Scandinavian Journal of Medicine & Science in Sports (in press)

Unaccustomed eccentric exercise may cause skeletal muscle damage with an increase in plasma creatine kinase (CK) activity. Although the wide variability among individuals in CK response to standardized ... [more ▼]

Unaccustomed eccentric exercise may cause skeletal muscle damage with an increase in plasma creatine kinase (CK) activity. Although the wide variability among individuals in CK response to standardized lengthening contractions has been well described, the reasons underlying this phenomenon have not yet been understood. Therefore, this study investigated a possible correlation of the changes in muscle damage indirect markers after an eccentric exercise with the decline in muscle performance during the exercise. Twenty-seven healthy untrained male subjects performed three sets of 30 maximal isokinetic eccentric contractions of the knee extensors. The muscular work was recorded using an isokinetic dynamometer to assess muscle fatigue by means of various fatigue indices. Plasma CK activity, muscle soreness, and stiffness were measured before (pre) and one day after (post) exercise. The eccentric exercise bout induced significant changes of the three muscle damage indirect markers. Large intersubject variability was observed for all criteria measured. More interestingly, the log (CKpost/CKpre) and muscle stiffness appeared to be closely correlated with the relative work decrease (r = 0.84, r2 = 0.70 and r = 0.75, r2 = 0.56, respectively). This is the first study to propose that the muscle fatigue profile during maximal eccentric protocol could predict the magnitude of the symptoms associated with muscle damage in humans. [less ▲]

Muscle intracellular and plasma free amino acid concentrations in Belgian Blue bulls on two different growth patterns

in Proceedings of the 7th Forum for Applied Biotechnology (1993)

Muscle performance in patients with fibromyalgia

in Joint Bone Spine (2002), 69(3), 293-299

Objectives. To compare muscle performance in women with fibromyalgia and in healthy women. Patients and methods. Sixteen women with fibromyalgia syndrome (FMS) and 85 healthy women who were physically ... [more ▼]

Objectives. To compare muscle performance in women with fibromyalgia and in healthy women. Patients and methods. Sixteen women with fibromyalgia syndrome (FMS) and 85 healthy women who were physically inactive or engaged in recreational sports underwent measurements of four parameters: maximal concentric isokinetic muscle strength of the knee extensors and flexors in the dominant limb, isometric grip strength on a Colin dynamometer, muscle fatigue resistance during 30 maximal concentric isokinetic contractions of the dominant knee flexors and extensors at 180° angular velocity, and static endurance during posture maintenance. Results. All muscle variables were decreased in the FMS patients as compared to the controls.The decreases were more marked during aerobic than during anaerobic exercise.Mean decreases were 39% (P<0.001) for muscle strength, 40% (P<0.0001) for fatigue resistance, and 81% (P<0.0001) for static endurance. Pain during exercise as evaluated using a visual analog scale was more marked in the FMS patients. Conclusion. This study of the three pathways supplying energy to muscle confirms that muscle function is globally impaired in FMS patients.The results suggest that the impairment predominates on aerobic processes. [less ▲]

Muscle protein turnover in double muscled Belgian Blue bulls during reduced and subsequent adequate energy and protein intake

in Symposium Lavoisier. Metabolic fuel selection (1994)

Muscle strength assessment after ACL reconstruction: Influence of the isokinetic testing modalities

in Journal of Rehabilitation Medicine Supplement (2008), 47

Muscles rotateurs d'épaule et isocinétisme

in Médecine et Hygiène (1993), 51

Muscular imbalance and acute lower extremity muscle injuries in sport

in International SportMed Journal (2004), 5(3), 169-176

Investigating factors associated with muscle strains highlight the multifactorial origin of the injury and the difficulty of identifying isolated or combined factors that caused the injury. Among the ... [more ▼]

Investigating factors associated with muscle strains highlight the multifactorial origin of the injury and the difficulty of identifying isolated or combined factors that caused the injury. Among the numerous causes reported in the literature, only a few have been scientifically associated with injury occurrence, while others have been empirically suggested. Contradictions in articles dealing with muscle strength and imbalance are frequent, and are probably the result of differences in methodology and criteria for patient inclusion. Imbalance in muscle strength commonly refers to abnormal bilateral asymmetry (between homologous groups) and a disruption of the agonist-antagonist ratio. Some authors who focus on a history of hamstring or adductor strains have demonstrated the frequent abnormality of muscle strength and balance by means of isokinetic assessment. Mixed ratios, combining the eccentric performance of “decelerating” muscles (such as the hamstrings) and the concentric performance of “mobiliser” muscles (such as the quadriceps) are suggested and seem relevant. An increased emphasis on eccentric strengthening exercises, particularly for the hamstrings, and ratio correction on the basis of statistically selected cut-offs, significantly reduces the recurrence rate of the injury and lingering complaints upon return-to-sport. Similarly, isokinetic interventions, as a preseason screening tool in sports where there is a high rate of muscle strain injuries, could detect imbalances early and thus promote a preventive strategy. [less ▲]

Muscular Performance Assessment of Trunk Extensors: A Critical Appraisal of the Literature

in Asghar Norasteh, Ali (Ed.) Low Back Pain (2012)

Muscular strength, functional performances and injury risk in professional and junior elite soccer players.

in Scandinavian Journal of Medicine & Science in Sports (2009), 19(2), 243-51

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 ... [more ▼]

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. [less ▲]

Musculation ou renforcement musculaire

in Xhardez, Yves (Ed.) Vade-mecum de Kinésithérapie et de rééducation fonctionnelle (2002)