Physiological strain to prolonged exercise bouts at the walk-run transition speeds depends on locomotion mode in healthy untrained men.

This study compared the physiological strain induced by prolonged walking and running performed at the walk-run transition speed (WRTS) in healthy untrained men. Twenty volunteers (age: 28 ± 5.01 years; height: 174.0 ± 0.3 cm; body mass: 74.5 ± 0.6 kg) underwent the following: (a) ramp-incremental maximal cardiopulmonary exercise test (CPET); (b) specific protocol to detect the WRTS; and (c) two 30-min walking and running bouts at WRTS (mean ± SD: 6.9 ± 0.06 km/h). Expired gases were collected during exercise bouts via the metabolic cart. A significant effect of locomotion mode (F = 4.8, P < 0.001) was observed with running resulting in higher cardiorespiratory responses than walking at the WRTS (oxygen uptake: mean difference = 0.26 L/min; pulmonary ventilation: mean difference = 5.53 L/min; carbon dioxide output: mean difference = 0.32 L/min; heart rate: mean difference = 13 beats/min; total energy expenditure: mean difference = 59 kcal). The rating of perceived exertion was similar across locomotion modes (mean difference = 0.3; P = 0.490). In conclusion, running promoted greater cardiorespiratory responses than walking at the WRTS in untrained healthy men. These data might have practical impact on aerobic training performed at intensities corresponding to WRTS.

Acute Hypotensive Response to Continuous and Accumulated Isocaloric Aerobic Bouts.

Evidence indicates that chronic reductions in blood pressure (BP) due to aerobic exercise depend on the ability to induce post-exercise hypotension (PEH) after each training bout. The purpose of this study was to investigate PEH after isocaloric bouts of continuous and accumulated running. 10 healthy pre-hypertensive men (aged 27.6±3.5 years) performed the following bouts of exercise: a) A continuous bout (CONT) expending a total of 400 kcal; and b) An accumulated bout split into 2×200 kcal (INTER1 and INTER2) to total 400 kcal at 75% of oxygen uptake reserve. BP, mean arterial pressure (MAP) and heart rate variability were monitored 10 min before and 60 min after control and all exercise conditions. The decrease in MAP over time after continuous (400 kcal) and accumulated (2×200 kcal) bouts of exercise was more pronounced than during control (mean diff between 1.6 and 5.4 mmHg, P≤0.01), although the magnitude of change was similar between continuous and accumulated bouts (mean diff=0.1 mmHg, P=0.79). Concomitant to the PEH, sympathovagal balance was inversely related to changes in MAP after isocaloric bouts performed continuously and cumulatively (r=- 0.72 and-0.85, P=0.019 and 0.002, respectively). In conclusion, BP decreased to similar levels after continuous and accumulated acute aerobic exercise matched for total energy expenditure. Our findings also indicate that the recovery pattern of cardiac autonomic activity may have an important role in eliciting PEH.

Hemodynamic Responses and Perceived Exertion During Continuous and Discontinuous Resistance Exercise.

This study compared acute responses of systolic and diastolic blood pressure (SBP/DBP), cardiac output (Q), heart rate (HR), stroke volume (SV), total peripheral resistance (TPR) and rate of perceived exertion (RPE) during resistance exercise performed continuously and discontinuously. Hemodynamic responses and RPE were assessed in the last of 4 sets of 12 repetitions of the knee extension with load corresponding to 70% of 12 repetition maximum, performed continuously (C) or discontinuously, with pauses of 5 s (D5) or 10 s (D10) interspersed in the middle of sets. The increase in SBP was higher for D10 (34.0±8.4%) and D5 (34.1±13.2%) vs. C (19.8±10.3%; P<0.001), while no difference was detected for DBP. Q (P=0.03) and SV (P=0.02) were higher, but HR was lower (P=0.04) in discontinuous vs. continuous. TPR remained stable during continuous, but significant decreases occurred during the pauses in the discontinuous protocols (P<0.001). The BP was higher in discontinuous than in continuous protocols, but the RPE was attenuated in discontinuous compared to continuous exercise. In conclusion, hemodynamic responses were exacerbated during resistance exercise performed discontinuously, but the perceived exertion was lowered.

Can Heart Rate Variability be used to Estimate Gas Exchange Threshold in Obese Adolescents?

This study investigated the agreement and reliability of oxygen uptake (V̇O2), V̇O2 reserve (V̇O2 R), heart rate (HR) and power output at intensities corresponding to the gas exchange threshold (GET) and heart rate variability threshold (HRVT) during maximal cardiopulmonary exercise testing (CPET) in obese and eutrophic adolescents. A further aim was to establish whether the HRVT was able to detect changes in cardio-respiratory fitness in obese adolescents after 3 months of recreational soccer practice. First, 25 obese and 10 eutrophic adolescents (ages 12-17) visited the laboratory twice to perform cycling CPET to test the reliability of CPET outcomes at GET and HRVT. Furthermore, the level of agreement between GET and HRVT was determined for a subgroup of 10 obese adolescents after performing a 3-month recreational soccer program. No significant difference was found for V̇O2, %V̇O2 R, HR and power output at the GET and HRVT (P>0.05), which were equally able to detect improvements in aerobic fitness after the soccer intervention. Correlations between GET and HRVT for V̇O2 and %V̇O2 R ranged from 0.89 to 0.95 (P<0.001) and test-retest reliability ranged from 0.59 to 0.82 (P<0.006). Overall, HRVT seems to be a reliable alternative for prescribing aerobic exercise intensity in obese adolescents.

Utility of a Non-Exercise VO2max Prediction Model for Designing Ramp Test Protocols.

This study investigated the validity of determining the final work rates of cycling and walking ramp-incremented maximal cardiopulmonary exercise tests (CPETs) using a non-exercise model to predict maximal oxygen uptake VO2max and the American College of Sports Medicine ACSM's metabolic equations. The validity of using this methodology to elicit the recommended test duration of between 8 and 12 min was then evaluated. First, 83 subjects visited the laboratory once to perform a cycling (n=49) or walking (n=34) CPET to investigate the validity of the methodology. Second, 25 subjects (cycling group: n=13; walking group: n=12) performed a CPET on 2 separate days to test the reliability of CPET outcomes. Observed VO2max was 1.0 ml·kg(-1)·min(-1) lower than predicted in the cycling CPET (P=0.001) and 1.4 ml·kg(-1)·min(-1) lower in the walking CPET (P=0.001). Only one of the 133 conducted CPETs was outside the test duration range of 8-12 min. Test-retest reliability was high for all CPET outcomes, with intraclass correlation coefficients of 0.90 to 0.99. In conclusion, the non-exercise model is a valid and reliable method for establishing the final work rate of cycling and walking CPETs for eliciting test durations of between 8 and 12 min.

Does prefrontal cortex transcranial direct current stimulation influence the oxygen uptake at rest and post-exercise?

The study evaluated the effect of transcranial direct current stimulation (tDCS) applied over prefrontal cortex on the oxygen uptake (V˙ O2) at rest and during post-exercise recovery. The V˙ O2 was assessed in eleven healthy subjects before, during tDCS (sham or anodal tDCS, 2 mA, 20 min), and 30-min following isocaloric aerobic exercise (~200 kcal). During tDCS, no changes were observed on V˙ O2 compared to baseline (P=0.95) and sham condition (P=0.85). The association between isocaloric exercise and anodal tDCS increased the V˙ O2 throughout 30-min recovery compared to sham condition (P<0.001). Therefore, the energy expenditure within the excess post-exercise oxygen consumption (EPOC) period, after anodal tDCS was approximately 19% higher compared to the sham condition (P<0.05). In conclusion, anodal tDCS applied on the prefrontal cortex combined with submaximal aerobic exercise increased the EPOC, enhancing the V˙ O2 and energy expenditure at least for 30-min of recovery.

Work volume in strength training is not affected by rest interval strategy.

AIM: Between-set rest intervals (RI) may be determined using exercise-recovery-ratio (ERR) or fixed periods. The study investigated the influence of different ERR and fixed RI on the training volume in sessions aiming for hypertrophy with upper-body exercises recruiting different muscle mass (bench press-BP and triceps extension-TE). METHODS: Sixteen men (25±2 years, 78±6 kg, 178±5 cm) with previous experience in resistance training performed 5 sets of maximum repetitions in each exercise with five RI protocols (RR1:3 [I3]; ERR1:5 [I5]; ERR1:7 [I7]; increasing ERR [IP] (1:3-1:5-1:7-1:9); 2-min fixed [2F]) in a counterbalanced design. The number of repetitions and work volume (load x repetitions) in each set and along the sessions (load x repetitions x sets) were compared across the RI protocols. RESULTS: The maximum repetitions decreased along with the sets in both exercises, but TE had lower percent decrease compared to BP, due to a longer time to perform the sets and therefore longer absolute rest time (P<0.05). The I3 exhibited the lowest repetitions sustainability (P<0.05). The training volume in I7, IP and 2F was always higher than I3 and I5 (P>0.05). However the absolute RI in 2F (~2 min) was shorter than in I7 and IP (~3 min), which reduced the total duration of the training session. CONCLUSION: Determining between-set RI based on ERR instead of using fixed intervals does not enable more work to be done in multiple-set/high intensity resistance training sessions.

Autonomic modulation following exercise is impaired in HIV patients.

UNLABELLED: The autonomic modulation in HIV patients undergoing highly active antiretroviral therapy (HAART) was investigated. The heart rate variability (HRV) was assessed in 13 HIV patients (43±2 years) and 10 healthy controls (31±5 years) at rest, during exercise, and recovery. All time (standard deviation of NN intervals, SDNN; root mean of squared sum of successive differences, rMSSD; relative number of pairs of adjacent RR intervals differing more than 50 ms, pNN50) and frequency (Low Frequency, LF; High Frequency, HF) HRV components were lower in HIV patients at rest [SDNN (HIV: 44.2±3.9 ms vs. CONTROL: 65.5±9.8 ms; P=0.04); rMSSD (HIV: 27.2±3.6 ms vs. CONTROL: 49.3±8.3 ms; P=0.02); pNN50 (HIV: 8.8±2.9% vs. CONTROL: 26.5±7.0%; P=0.02); LF (HIV: 502.4±80.5 ms2 vs. CONTROL: 1302.8±446.4 ms2; P=0.04); HF (HIV: 296.4 ± 62.3 ms2 vs. CONTROL: 986.3±280.6 ms2; P=0.01)] and post-exercise [SDNN (HIV: 32.3±3.5 ms vs. CONTROL: 55.8±5.9 ms; P=0.002); rMSSD (HIV: 17.4±3.1 ms vs. CONTROL: 36.6±4.6 ms; P=0.002); pNN50 (HIV: 2.9±1.2% vs. CONTROL: 14.7±3.4%; P=0.001); LF (HIV: 404.9±102.6 ms2 vs. CONTROL: 910.1±214.2 ms2; P=0.03); HF (HIV: 147.6 ± 40.1 ms vs. CONTROL: 554.5±135.0 ms2; P=0.004)]. No between-group differences were found during exercise (P>0.05 for all comparisons). In conclusion, HIV patients showed impaired autonomic modulation, with reduced parasympathetic activity at rest and during post-exercise recovery.

Aerobic exercise intensity influences hypotension following concurrent exercise sessions.

The study investigated whether resistance and aerobic concurrent exercise (CE) with different intensities influenced postexercise hypotension (PEH). 21 healthy men (20.7±0.7 yr) performed 4 sessions: control [CTL 60 min of rest], and CE1, CE2, and CE3 consisting respectively of 2 sets of 6 exercises at 80% 1RM followed by 30 min of cycle ergometer exercise at 50%, 65%, and 80% of peak oxygen consumption (VO2peak). All sessions lasted approximately 60 min and began with resistance prior to aerobic sessions. Systolic (SBP) and diastolic (DBP) blood pressure (BP) were assessed at baseline and every 10 min during 120-min recovery. The magnitude of SBP decrease was similar after all CE sessions [CE1: 4.2±2.5 mmHg; CE2: 4.8±2.7 mmHg; CE3: 6.0±2.0 mmHg; p=0.06], but the PEH lasted approximately 1 h longer following CE2 and CE3 [120 min] compared to CE1 [60-70 min] (P<0.05). The magnitude of DBP decrease was slightly greater after CE3 and CE2 [2 mmHg] than after CE1 [1 mmHg] (P<0.05), being longer following CE3 [60 min] compared to CE2 and CE1 [40 min] (P<0.05). In conclusion, CE sessions combining resistance and aerobic sessions elicited PEH, especially when the intensity of the aerobic exercise was higher than 65% VO2peak.

Walk-run transition in young and older adults: with special reference to the cardio-respiratory responses.

Cardio-respiratory responses of young and older subjects performing walking and running protocols at the walk-run transition speed (WRT) were compared. A total of 26 volunteers assigned to younger (YG, 24 +/- 3 years) and older (OG, 64 +/- 6 years) groups underwent a protocol to determine the WRT used in 6-min walking and running protocols. Oxygen uptake (VO(2)), ventilation (V (E)), expired carbon dioxide (VCO(2)), heart rate (HR) and perceived exertion (RPE) were assessed. Oxygen pulse (O(2) pulse) and respiratory exchange ratio (RER) were calculated. The WRT was not different between groups (OG: 6.84 +/- 0.69 km h(-1) vs. YG: 7.04 +/- 0.77 km h(-1), P = 0.62). No between-group differences were found within a given gait pattern for VO(2) (P = 0.061) and VCO(2) (P = 0.076). However, VO(2) (P = 0.0022) and VCO(2) (P = 0.0041) increased in OG when running, remaining stable in YG (VO(2): P = 0.622; VCO(2): P = 0.412). The VE was higher in OG compared to YG in walking (P = 0.030) and running (P = 0.004) protocols. No age-related (P = 0.180) or locomotion (P = 0.407) effects were found for RER. The HR increased in OG and between-group difference was detected while running (P = 0.003). No within- (P = 0.447) or between-group (P = 0.851) difference was found for O(2) pulse. The net VO(2) increased from walking to running in OG (P < 0.0001) but not in YG (P = 0.53), while RPE was lower in YG (P = 0.041) but stable in OG (P = 0.654). In conclusion, the WRT speed was similar across the age groups. However, the VO(2) and VCO(2) increase from walking to running was larger for OG than YG. The HR, VE and RPE were also higher when running in OG compared to YG. Therefore, the locomotion strategy had different impacts on the metabolic demand of older and younger subjects.

Influence of cardiopulmonary exercise testing protocol and resting VO(2) assessment on %HR(max), %HRR, %VO(2max) and %VO(2)R relationships.

The findings of previous studies investigating the strength of the relationships between the percentages of maximal heart rate (%HR(max)), heart rate reserve (%HRR), maximal oxygen uptake (%VO(2max)), and oxygen uptake reserve (%VO(2)R) have been equivocal. This inconsistency between studies could largely be due to differences in methodology. The purpose of this study was therefore to determine whether different VO(2max) test protocols and resting VO(2) assessment influence the relationships between the %HR(max), %HRR, %VO(2max), and %VO(2)R. Thirty-three young men performed maximal treadmill protocols (ramp, Bruce) to assess HR(max) and VO(2max). Resting VO(2) was assessed as follows: a) resting VO(2standard), using strict criteria (24 h exercise abstention, alcohol, soft drinks, or caffeine; 8 h fasting; 30 min assessment); b) resting VO(2sitting) and; c) resting VO(2standing) (both 5 min before exercise testing). The %HRR was closer to %VO(2max) than to %VO(2)R, especially in the ramp protocol (p<0.001). In the Bruce protocol, relationships were closer to the identity line, and there was no significant difference between %HRR and %VO(2max), or %VO(2)R. The VO(2max) was significantly higher in the ramp protocol compared to the Bruce protocol (p<0.001). In both protocols resting VO(2) assessment produced no significant difference in the intercepts and slopes of the %HRR-%VO(2)R relationships obtained from individual regression models. The %VO(2)R calculated using resting VO(2standard) was closer to %HRR compared to VO(2sitting) and VO(2standing). The premise that %HRR is more strongly related to %VO(2)R than to %VO(2max) was not confirmed. Methodological differences should be considered when interpreting previous studies investigating %HR(max), %HRR, %VO(2max), and %VO(2)R relationships.

Effects of age and rest interval on strength recovery.

The purpose of this study was to compare the effect of two different rest intervals between sets of isokinetic knee extension exercise on peak torque (PT), and Total Work (TW) between untrained younger and older men. Seventeen young men (24.22+/-2.58 yrs) and 20 older men (66.85+/-4.02 yrs) performed 3 sets of 10 unilateral isokinetic knee extension repetitions at 60 degrees /s. The rest intervals between sets were 1 and 2 min. There was a significant decline in PT when 1 and 2 min rest intervals were used for young men, but not when a 2 min rest interval was applied for old men. There was also a significant decline in TW among the 3 sets when 1 and 2 min rest intervals were applied for young men, whereas the decline in TW in older men occurred only between the 2(nd) and 3(rd) sets. PT and TW in the 3(rd) set were significant greater following a 2 min rest interval than a 1 min rest in both young and older men. The present study indicated that non-resistance trained young men may require longer rest interval to recover full PT and TW when compared to older men.

Effects of a supervised exercise program on the physical fitness and immunological function of HIV-infected patients.

AIM: Exercise effects in subjects with HIV/AIDS are not entirely understood. The study aimed to investigate the effects of a supervised exercise program on the physical fitness and immunological function of HIV-infected subjects. METHODS: Twenty-seven highly active antiretroviral therapy treated HIV-infected patients (age: 45±2 years; CD4-T: 21.3±2.2%) were assigned to a control (CG, n=8) or experimental (EG, n=19) group. The EG participated in a 12-week exercise program, consisting of aerobic training, strength, and flexibility exercises (3 times/wk; aerobic-30min: PWC 150; strength-50min: 3 sets of 12 reps of 5 exercises at 60-80% 12 RM; flexibility-10min: 2 sets of 30 s at maximal range of motion of 8 exercises). RESULTS: Prior to training there was no significant difference in any variable between the EG and the CG. Flexibility (23%, P<0.05), 12 repetition maximum in the leg press and seated bilateral row exercises (54% and 65% respectively, P<0.05) increased, while the heart rate at a given cycle ergometer workload declined (19% for slope and 12% for intercept, P<0.05) in the EG, but not in the CG. No significant differences were found for the relative and absolute CD4 T-cell counts between groups prior to or after training, but there was a slight enhancement trend in the EG (16%, P=0.19). CONCLUSION: Overall training can improve the muscle and aerobic fitness of HIV-infected patients with no negative effect on their immunological function.

Oxygen uptake, respiratory exchange ratio, or total distance: a comparison of methods to equalize exercise volume in Wistar rats.

This study compared strategies to equalize the volume of aerobic exercise performed with different intensities by Wistar rats, based on the distance covered during exercise bouts and energy expenditure (EE, isocaloric sessions) obtained from oxygen uptake (V̇O2) or respiratory exchange ratio (RER). Thirty-three male rats (270.5±12.8 g) underwent maximal exercise tests to determine V̇O2 reserve (V̇O2R), being randomly assigned to three groups: moderate-intensity continuous exercise at speed corresponding to 50% V̇O2R (MIC; n=11); high-intensity continuous exercise at 80% V̇O2R (HIC; n=11); and high-intensity intermittent exercise (HII; n=11) at 60% V̇O2R (3 min) and 80% V̇O2R (4 min). Exercise duration was calculated individually to elicit EE of 5 kcal in each session. No difference between groups was found for total running distance (MIC: 801±46, HIC: 734±42, HII: 885±64 m; P=0.13). Total EE measured by RER was systematically underestimated compared to values obtained from V̇O2 (HII: 4.5% and MIC: 6.2%, P<0.05). Total EE (calculated from V̇O2), and duration of HIC bouts (2.8 kcal and 30.8±2.2 min) were lower (P<0.0001) than in MIC (4.9 kcal and 64.7±1.8 min) and HII (4.7 kcal and 46.9±2.2 min). Predicted and actual values of total V̇O2, total EE, and duration of isocaloric sessions were similar in MIC and HII (P>0.05), which were both higher than in HIC (P<0.0001). In conclusion, the time to achieve a given EE in exercise bouts with different intensities did not correspond to the total distance. Therefore, the volume of aerobic exercise in protocols involving Wistar rats should be equalized using EE rather than total covered distance.

Spectral analyses of systolic blood pressure and heart rate variability and their association with cognitive performance in elderly hypertensive subjects.

Systolic hypertension is associated with cognitive decline in the elderly. Altered blood pressure (BP) variability is a possible mechanism of reduced cognitive performance in elderly hypertensives. We hypothesized that altered beat-to-beat systolic BP variability is associated with reduced global cognitive performance in elderly hypertensive subjects. In exploratory analyses, we also studied the correlation between diverse discrete cognitive domains and indices of systolic BP and heart rate variability. Disproving our initial hypothesis, we have shown that hypertension and low education, but not indices of systolic BP and heart rate variability, were independent predictors of lower global cognitive performance. However, exploratory analyses showed that the systolic BP variability in semi-upright position was an independent predictor of matrix reasoning (B = 0.08 ± .03, P-value = 0.005), whereas heart rate variability in semi-upright position was an independent predictor of the executive function score (B = -6.36 ± 2.55, P-value = 0.02). We conclude that myogenic vascular and sympathetic modulation of systolic BP do not contribute to reduced global cognitive performance in treated hypertensive subjects. Nevertheless, our results suggest that both systolic BP and heart rate variability might be associated with modulation of frontal lobe cognitive domains, such as executive function and matrix reasoning.

Influence of exercise modality on agreement between gas exchange and heart rate variability thresholds.

The main purpose of this study was to investigate the level of agreement between the gas exchange threshold (GET) and heart rate variability threshold (HRVT) during maximal cardiopulmonary exercise testing (CPET) using three different exercise modalities. A further aim was to establish whether there was a 1:1 relationship between the percentage heart rate reserve (%HRR) and percentage oxygen uptake reserve (%VO2 R) at intensities corresponding to GET and HRVT. Sixteen apparently healthy men 17 to 28 years of age performed three maximal CPETs (cycling, walking, and running). Mean heart rate and VO2 at GET and HRVT were 16 bpm (P<0.001) and 5.2 mL · kg(-1) · min(-1) (P=0.001) higher in running than cycling, but no significant differences were observed between running and walking, or cycling and walking (P>0.05). There was a strong relationship between GET and HRVT, with R2 ranging from 0.69 to 0.90. A 1:1 relationship between %HRR and % VO2 R was not observed at GET and HRVT. The %HRR was higher during cycling (GET mean difference=7%; HRVT mean difference=11%; both P<0.001), walking (GET mean difference=13%; HRVT mean difference=13%; both P<0.001), or running (GET mean difference=11%; HRVT mean difference=10%; both P<0.001). Therefore, using HRVT to prescribe aerobic exercise intensity appears to be valid. However, to assume a 1:1 relationship between %HRR and % VO2 R at HRVT would probably result in overestimation of the energy expenditure during the bout of exercise.

Effects of Growth Hormone Administration on Muscle Strength in Men over 50 Years Old.

Growth hormone (GH) use has been speculated to improve physical capacity in subjects without GH deficiency (GHD) through stimulation of collagen synthesis in the tendon and skeletal muscle, which leads to better exercise training and increased muscle strength. In this context, the use of GH in healthy elderly should be an option for increasing muscle strength. Our aim was to evaluate the effect of GH therapy on muscle strength in healthy men over 50 years old. Fourteen healthy men aged 50-70 years were evaluated at baseline for body composition and muscle strength (evaluated by leg press and bench press exercises, which focus primarily on quadriceps-lower body part and pectoralis major-upper body part-muscles, resp.). Subjects were randomised into 2 groups: GH therapy (7 subjects) and placebo (7 subjects) and reevaluated after 6 months of therapy. Thirteen subjects completed the study (6 subjects in the placebo group and 7 subjects in the GH group). Subjects of both groups were not different at baseline. After 6 months of therapy, muscle strength in the bench press responsive muscles did not increase in both groups and showed a statistically significant increase in the leg press responsive muscles in the GH group. Our study demonstrated an increase in muscle strength in the lower body part after GH therapy in healthy men. This finding must be considered and tested in frail older populations, whose physical incapacity is primarily caused by proximal muscle weakness. The trial was registered with NCT01853566.

Identification of sarcopenic obesity in postmenopausal women: a cutoff proposal.

Sarcopenic obesity is the combination of reduced fat-free mass (FFM) and increased fat mass (FM) with advancing age but there is lack of clear criteria for its identification. The purposes of the present investigation were: 1) to determine the prevalence of postmenopausal women with reduced FFM relative to their FM and height, and 2) to examine whether there are associations between the proposed classification and health-related variables. A total of 607 women were included in this cross-sectional study and were separated into two subsets: 258 older women with a mean age of 66.8 ± 5.6 years and 349 young women aged 18-40 years (mean age, 29.0 ± 7.5 years). All volunteers underwent body composition assessment by dual-energy X-ray absorptiometry. The FFM index relative to FM and height was calculated and the cutoff value corresponded to two standard deviations below the mean of the young reference group. To examine the clinical significance of the classification, all older participants underwent measurements of quadriceps strength and cardiorespiratory fitness. Values were compared between those who were classified as low FFM or not, using an independent samples t-test and correlations were examined. The cutoff corresponded to a residual of -3.4 and generated a sarcopenic obesity prevalence of 19.8% that was associated with reduced muscle strength and aerobic fitness among the older participants. Also, the index correlated significantly with the health-related fitness variables. The results demonstrated reduced functional capacity for those below the proposed cutoff and suggested applicability of the approach as a definition for sarcopenic obesity.

Oxygen uptake, respiratory exchange ratio, or total distance: a comparison of methods to equalize exercise volume in Wistar rats

This study compared strategies to equalize the volume of aerobic exercise performed with different intensities by Wistar rats, based on the distance covered during exercise bouts and energy expenditure (EE, isocaloric sessions) obtained from oxygen uptake (V̇O2) or respiratory exchange ratio (RER). Thirty-three male rats (270.5±12.8 g) underwent maximal exercise tests to determine V̇O2 reserve (V̇O2R), being randomly assigned to three groups: moderate-intensity continuous exercise at speed corresponding to 50% V̇O2R (MIC; n=11); high-intensity continuous exercise at 80% V̇O2R (HIC; n=11); and high-intensity intermittent exercise (HII; n=11) at 60% V̇O2R (3 min) and 80% V̇O2R (4 min). Exercise duration was calculated individually to elicit EE of 5 kcal in each session. No difference between groups was found for total running distance (MIC: 801±46, HIC: 734±42, HII: 885±64 m; P=0.13). Total EE measured by RER was systematically underestimated compared to values obtained from V̇O2 (HII: 4.5% and MIC: 6.2%, P<0.05). Total EE (calculated from V̇O2), and duration of HIC bouts (2.8 kcal and 30.8±2.2 min) were lower (P<0.0001) than in MIC (4.9 kcal and 64.7±1.8 min) and HII (4.7 kcal and 46.9±2.2 min). Predicted and actual values of total V̇O2, total EE, and duration of isocaloric sessions were similar in MIC and HII (P>0.05), which were both higher than in HIC (P<0.0001). In conclusion, the time to achieve a given EE in exercise bouts with different intensities did not correspond to the total distance. Therefore, the volume of aerobic exercise in protocols involving Wistar rats should be equalized using EE rather than total covered distance.