Biceps femoris and semitendinosus: teammates or competitors? : new insights into hamstring injury mechanisms in male football players : a muscle functional MRI study

Background: The hamstring injury mechanism was assessed by investigating the exercise-related metabolic activity characteristics of the hamstring muscles using a muscle functional MRI (mfMRI) protocol. Methods: 27 healthy male football players and 27 football players with a history of hamstring injuries (recovered and playing fully) underwent standardised mfMR Imaging. The mfMRI protocol consisted of a resting scan, a strenuous bilateral eccentric hamstring exercise and a postexercise scan. The exercise-related T2 increase or the signal intensity shift between both scans was used to detect differences in metabolic activation characteristics (1) between the different hamstring muscle bellies and (2) between the injury group and the control group. Results: A more symmetrical muscle recruitment pattern corresponding to a less economic hamstring muscle activation was demonstrated in the formerly injured group (p<0.05). The injured group also demonstrated a significantly lower strength endurance capacity during the eccentric hamstring exercise. Conclusions: These findings suggest that the vulnerability of the hamstring muscles to football-related injury is related to the complexity and close coherence in the synergistic muscle recruitment of the biceps femoris and the semitendinosus. Discrete differences in neuromuscular coordination and activity distribution, with the biceps femoris partly having to compensate for the lack of endurance capacity of the semitendinosus, probably increase the hamstring injury risk

Functional assessment of the cervical spine in F-16 pilots with and without neck pain

Introduction: Spinal symptoms in fighter pilots are a serious aeromedical problem. The most common neck complaints are muscular pain and strain. The aim of the current study was to determine possible differences in the cervical range of motion (CROM), neck position sense, and neck muscle strength between pilots with and without neck pain. Methods: There were 90 male F-I 6 pilots who volunteered, of which 17 had experienced bilateral neck pain. A standardized questionnaire was used to collect personal information. The maximum isometric neck flexion/extension and lateral flexion strength, the neck position sense, and the cervical range of motion were measured. Results: There were no significant differences between healthy pilots and those with neck pain concerning neck Muscle strength and neck position sense. The neck pain group had a limited CROM in the sagittal plane (130 degrees; CI: 116 degrees-144 degrees) and in the transversal plane (155 degrees; CI: 140 degrees-170 degrees) compared to the healthy pilots. Discussion: In the current study we screened for different motor skills so that deficits Could be detected and retraining programs could be implemented when necessary. According to our results, individual retraining programs might reduce neck pain and therefore a well-instructed training program to maintain a proper active CROM should be implemented. Future Studies should investigate the effectiveness of this kind of program

The effects of a neoprene knee sleeve on subjects with a poor versus good joint position sense subjected to an isokinetic fatigue protocol

Objectives: It has been shown that muscle fatigue has a negative influence on proprioception. Several studies already have demonstrated improvement of proprioception by using knee sleeves. Hypothesis: Neoprene knee sleeves have different effects on the joint position sense in locally fatigued subjects with good or poor proprioceptive acuity. Design: A true experimental design with random assignment to intervention and control limbs. Setting: Military hospital, department of physical medicine and rehabilitation. Participants: Sixty-four healthy subjects. Interventions: All subjects underwent four consecutive assessments of the same active joint-repositioning test under different conditions (braced, nonbraced, fatigued, and nonfatigued). Main Outcome Measurements: A three-way analysis of variance with repeated-measures design was conducted to investigate the effects of side (braced versus control side), assessment sequence (one to four), and proprioceptive acuity ("good" versus "poor"), and their interactive effect on the joint position sense. Results: Post hoe analysis revealed that only subjects with "poor" proprioceptive acuity benefit from the braced condition before the isokinetic fatigue protocol (P < 0.001). In contrast, all subjects benefit from the braced condition after the fatigue test. Conclusions: Bracing is helpful in individuals with a poor baseline proprioceptive acuity in both fatigued and nonfatigued states. Subjects with a good joint position sense benefit from bracing only when in a fatigued state. The present findings suggest a rationale for using neoprene knee sleeves as a preventative measure or treatment in subjects and patients to enhance proprioceptive acuity in a fatigued state. Classification into "poor" and "good" proprioceptive acuity is only relevant in the nonfatigued condition