Cardiorespiratory and metabolic demand of the 6-minute pegboard and ring test in healthy young adults.

OBJECTIVE: To determine the cardiorespiratory and metabolic demand of the Six-Minute Pegboard and Ring Test (6PBRT) in healthy young adults and its association with maximal arm cycle ergometer test (arm CET). METHODS: Volunteers were randomized to performed the 6PBRT test or arm CET. The second test was performed after 48 h. Oxygen consumption (VO2), heart rate (HR), dyspnea and upper limb fatigue were assessed during the tests. Demographic data, body composition, level of physical activity, arm strength and endurance were also evaluated. RESULTS: During 6PBRT, VO2 values increased from 5.8 to 11.1 mL kg-1.min-1 (p < 0.001). VO2peak, HR Mean and HRmax at 6PBRT were 47.2% and close to 65% respectively of those achieved during the arm CET. There was a positive correlation between the score on 6PBRT and VO2mean and VO2peak achieved at arm CET (r = 0.268; p = 0.003 and r = 0.247; p = 0.046 respectively). No correlation was found between the HRmean, HRpeak, level of physical activity or strength with 6PBRT (p > 0.05). Handgrip endurance had a positive correlation with score on 6PBRT (r = 0.237; p = 0.054). Body Mass Index, body fat and fat mass were negatively correlated with the score on 6PBRT (r = 0.301; p = 0.014, 0.329; p = 0.007 and r = 0.427; p = 0.001). CONCLUSIONS: The 6PBRT test showed a moderate cardiorespiratory and metabolic demand in healthy individuals in comparison of arm CET. BMI, body fat and fat mass correlated with the score on 6PBRT.

Prior aerobic physical training modulates neuropeptide expression and central thermoregulation after ovariectomy in the rat.

This study compared the effects of aerobic physical training and estradiol (E2) replacement on central pathways involved with thermoregulation in ovariectomized rats. Rats were assigned to untrained ovariectomized treated with placebo (UN-OVX), untrained ovariectomized treated with E2 (E2-OVX), and trained ovariectomized (TR-OVX) groups. Tail skin temperature (TST), internal temperature (Tint), and basal oxygen consumption (VO2) were recorded. Neuronal activity, brain expression of Kiss1, NKB and Prodyn, and central norepinephrine (NE) levels were measured. UN-OVX had the highest TST. Compared to UN-OVX rats, TR-OVX and E2-OVX had lower Fos expression in the paraventricular and arcuate (ARC) nuclei, and lower double labeling for Tyrosine Hydroxylase and Fos in the brainstem. Compared to UN-OVX, only TR-OVX group exhibited lower kisspeptin (Kiss1), neurokinin B (NKB), and prodynorphin expression in the ARC and higher central NE levels. Aerobic physical training before menopause may prevent the heat dissipation imbalance induced by reduction of E2, through central NE release, modulation of Kiss1, NKB and prodynorphin expression in neurons from ARC nucleus.

Whole body vibration in the static modified push-up position in untrained healthy women stimulates neuromuscular system potentiating increased handgrip myogenic response.

OBJECTIVE: To investigate the acute effect of whole-body vibration (WBV) on handgrip strength (HS) and electromyographic activity of the flexor digitorum superficialis muscle of healthy women in the static push-up position. METHODS: Twenty-eight women received four experimental tests in a randomized order: A) Control - rest in seating position with feet on the floor and hands in the supine position on the lower limbs. There was no vibration stimulus; B) Placebo - push-up position with their hands on the vibratory platform that remained disconnected, but with a sonorous stimulus mimicking the vibration; C) Low vibration and D) High vibration - push-up position with their hands on the vibratory platform using one of the vibratory stimulus intensity: low vibration: 25 Hz/2 mm/49.30 m s-2; or high vibration: 45 Hz/2 mm/159.73 m s-2. Participants remained 5 min in each situation. HS and electromyography (EMG) were performed at baseline and after all four experimental tests. The index of neural efficiency (i.e. the ratio between EMG and HS) was also calculated to determine the efficiency of muscle contraction. Statistical analysis was performed by ANOVA two-way design mixed test with Tukey's post hoc test, being considered significant p < 0.05. RESULTS: High vibration increased HS compared with all the other experimental tests (p = 0.0006, F = 6.03). There was a reduction of EMG activity of the flexor digitorum superficialis muscle only after high vibration (p = 0.0135, F = 6.22), which was accompanied by lower values of the index of neural efficiency after intervention (between-group difference, p = 0.0002, F = 0.674). CONCLUSION: WBV in the push-up position has an acute positive effect on HS accompanied by a lower index of neural efficiency, providing a better efficiency of muscle contraction.