Fat mass is negatively associated with the physiological ability of tissue to consume oxygen

To describe the relationship between variables related to body composition and peak oxygen uptake ( V˙O2 peak) and to verify whether fat mass can affect these relationships. Methods: Eighty participants underwent cardiopulmonary exercise testing to measure V˙O2 peak and a body composition assessment to measure fat mass, fat free mass (FFM), and total body mass (BM). Results: There were significant relationships between V˙O2 peak relative to FFM (fat free mass) (mL/kgFFM/min) and absolute fat mass (kg) (r=-0.50, p<0.001) and relative fat mass (%) (r=-0.56, p<0.001). Absolute V˙O2 peak (L/min) had a high positive relationship with FFM (r=0.83, p<0.0001); the relationship between V˙O2 peak (L/min) and FFM remained high and positive even when accounting for absolute fat mass (kg) (r=0.83, p<0.001). V˙O2 peak relative to total body mass (mL/kgBM/min) showed a high negative relationship with relative fat mass (%) (r=-0.89, p<0.001) and a positive relationship with fat free mass (kg) (r=0.57, p<0.001), which did not change when accounting for fat mass (kg) (r=0.56, p<0.001). Conclusion: These data indicate that the physiological ability of tissue to consume oxygen ( V˙O2 peak in mL/kgFFM/min) is negatively associated with fat mass. Moreover, the individual's cardiorespiratory capacity to transport oxygen for working muscles ( V˙O2 peak in L/min) is strongly related to absolute FFM, and this association is not affected by fat mass. Finally, a better body mass composition (high FFM and low fat mass) is important for aerobic physical fitness ( V˙O2 peak in mL/kgBM/min) and improved physiological ability of tissue to consume oxygen ( V˙O2 peak in mL/kgFFM/min).(AU)

Differences in muscle strength after ACL reconstruction do not influence cardiorespiratory responses to isometabolic exercise

Objectives: To investigate whether the muscle strength decrease that follows anterior cruciate ligament (ACL) reconstruction would lead to different cardiorespiratory adjustments during dynamic exercise. Method: Eighteen active male subjects were submitted to isokinetic evaluation of knee flexor and extensor muscles four months after ACL surgery. Thigh circumference was also measured and an incremental unilateral cardiopulmonary exercise test was performed separately for both involved and uninvolved lower limbs in order to compare heart rate, oxygen consumption, minute ventilation, and ventilatory pattern (breath rate, tidal volume, inspiratory time, expiratory time, tidal volume/inspiratory time) at three different workloads (moderate, anaerobic threshold, and maximal). Results: There was a significant difference between isokinetic extensor peak torque measured in the involved (116.5±29.1 Nm) and uninvolved (220.8±40.4 Nm) limbs, p=0.000. Isokinetic flexor peak torque was also lower in the involved limb than in the uninvolved limb (107.8±15.4 and 132.5±26.3 Nm, p=0.004, respectively). Lower values were also found in involved thigh circumference as compared with uninvolved limb (46.9±4.3 and 48.5±3.9 cm, p=0.005, respectively). No differences were found between the lower limbs in any of the variables of the incremental cardiopulmonary tests at all exercise intensities. Conclusions: Our findings indicate that, four months after ACL surgery, there is a significant deficit in isokinetic strength in the involved limb, but these differences in muscle strength requirement do not produce differences in the cardiorespiratory adjustments to exercise. Based on the hypotheses from the literature which explain the differences in the physiological responses to exercise for different muscle masses, we can deduce that, after 4 months of a rehabilitation program after an ACL reconstruction, individuals probably ...

Shoulder isokinetic profile of male handball players of the Brazilian National Team

BACKGROUND: Data obtained on an isokinetic dynamometer are useful to characterize muscle status and have been reported in muscle imbalance studies in different types of sport. However, few studies have assessed elite handball players to establish reference values. OBJECTIVE: The purpose of this study was to compare, for the dominant (D) and non-dominant (ND) side, the isokinetic profile of shoulder rotator muscle strength between male handball players (H) and asymptomatic non-athletes (NA). METHOD: Isokinetic concentric and eccentric strength tests for D upper limbs were performed by the H group (n=20) and the NA group (n=12). Internal and external rotator muscle peak torque in concentric action was assessed at 60°/s and 300°/s and in eccentric action at 300°/s. We also calculated conventional balance (the ratio of external rotator peak torque to internal rotator peak torque in concentric action) and functional balance (the ratio of external rotator peak torque in eccentric action to internal rotator peak torque in concentric action). RESULTS: In the H group, dominant limbs were stronger in concentric action for external rotation at 60 and 300°/s. The conventional balance ratio for the D side was significantly lower at 60 and 300°/s for H compared to NA. The functional ratio for the D side was significantly lower at 300º/s for H compared to NA. CONCLUSIONS: Compared to asymptomatic non-athletes, handball players presented significant muscular imbalance resulting from daily sports practice, a known risk factor for shoulder injuries. .