Influence of full range of motion vs. equalized partial range of motion training on muscle architecture and mechanical properties.

PURPOSE: The purpose of this study was to determine the effect of a 15-week partial range of motion (ROM) resistance training program on the vastus lateralis (VL) architecture and mechanical properties, when the time under tension (TUT) was equalized. METHODS: Nineteen untrained male subjects were randomly assigned to a control (Control; n = 8) or training (TG; n = 11) group. In the TG, the dominant and nondominant legs were randomly selected to be trained with a full ROM (FULL) or a partial ROM (PART) in an isokinetic dynamometer. Training volume was equalized based on the TUT by manipulating sets and repetitions. The VL muscle architecture was assessed by B-mode ultrasonography at rest and during maximal isometric knee extension contractions (MVCs) at ten knee angles. The VL fascicle force and specific tension were calculated from the MVCs with superimposed stimuli, accounting for the moment arm length, muscle architecture, and antagonist coactivation. RESULTS: The FULL training induced changes in fascicle length (FL) (4.9 ± 2.0%, P < 0.001) and specific tension (25.8 ± 18.7%, P < 0.001). There was a moderate effect of PART training on the physiological cross-sectional area (PCSA) (7.8 ± 4.0%, P < 0.001, dav = 0.6) and torque-angle adaptations (average increase 17.7 ± 3.9%, P < 0.05). CONCLUSIONS: These results provide evidence that crucial architectural and mechanical muscle adaptations are dependent on the ROM used in strength training. It seems that muscle FL and specific tension can be increased by pure concentric training if greater ROM is used. Conversely, restricting the ROM to shorter muscle lengths promotes a greater PCSA and angle-specific strength adaptations.

Associations between self-rated health with cardiorespiratory fitness and obesity status among adolescent girls.

BACKGROUND: The main goal of this study was to analyze the associations between cardiorespiratory fitness (CRF) and body mass index (BMI) with self-rated health (SRH) of adolescent girls. METHODS: This was a cross-sectional study of 533 adolescents girls, aged from 10 to 18 years old. CRF was predicted by maximal multistage 20-m shuttle-run test according to procedures described from FITNESSGRAM. Girls' obesity status was classified according to International Obesity Task Force and Self-rated health (SRH) was assessed by questionnaire. RESULTS: The findings showed that among adolescent girls 23.2% had negative SRH. Girls who were classified as unfit were more likely to report negative SRH in both univariate logistic (OR: 3.05; CI: 1.91-4.87; P < .05) and multivariate (OR: 2.93; CI: 1.82-4.72; P < .05) regression analyses compared with their fit peers. Obese girls were more likely to report negative SRH (OR: 2.30; CI: 1.14-4.62; P < .05) compared with their normal-weight counterparts. However such association was lost in multivariate analyses suggesting an effect of CRF. CONCLUSIONS: Negative perception of health was associated with lower CRF and weight status although such association it is mediated by CRF condition.