The effects of physical fitness and body composition on oxygen consumption and heart rate recovery after high-intensity exercise

Relationships among Physical Fitness, External Loads, and Heart Rate Recovery: A Study on Futsal Players during an Overseas Congested-Weeks Training Camp

This study examined relationships among players' physical characteristics, match external loads, and heart rate recovery (HRR) during match substitutions in a congested fixture of an overseas futsal training camp. Eleven under-20 national futsal players' anthropometric characteristics (age, body height, body mass, % fat, and % muscle) and physical fitness [HRmax, VO2max, maximal aerobic speed (MAS) during the 30-15 intermittent fitness test (IFT)] were determined. Additionally, locomotion profiles during field play and HRR sitting on the bench were recorded during five matches. A repeated-measures analysis of variance and Pearson's correlation coefficient were used for statistical analysis. The results revealed that the overall observed correlations among anthropometry, body composition, physical fitness, and HRR were inconsistent across all the matches and substitutions. However, the numbers of moderate (1.00-1.99 m/s2), moderate-to-high (2.00-2.99 m/s2), and high (3.00-50.00 m/s2) intensities of acceleration presented negative correlations in the last match (r < -0.76; p < 0.05). HRR during match substitutions may have been influenced by uncontrolled factors across all the match play and recovery. HRR measures may be affected mainly by fatigue caused by the accumulation of accelerations throughout a congested fixture during a congested-schedule of a futsal training camp.

Sex-Related Differences in Oxygen Consumption Recovery After High-Intensity Rowing Exercise During Childhood and Adolescence

PURPOSE

To determine sex-related differences in oxygen consumption (V˙O2) recovery after high-intensity exercise during childhood and adolescence.

METHODS

Forty-two boys and 35 girls (10-17 y) performed a 60-second all-out test on a rowing ergometer. Postexercise V˙O2 recovery was analyzed from (1) the V˙O2 recovery time constant obtained from a biexponential model (τ1V˙O2) and (2) excess postexercise oxygen consumption calculated over a period of 8 minutes (EPOC8) and until τ1V˙O2 was reached (EPOCτ1). Multiplicative allometric modeling was used to assess the concurrent effects of body mass or lean body mass, and age on EPOC8 and EPOCτ1.

RESULTS

EPOC8 increased significantly more in boys from the age of 14 years. However, the sex difference was no longer significant when EPOC8 was analyzed using an allometric model including body mass + age or lean body mass + age. In addition, despite a greater increase in EPOCτ1 in boys from the age of 14 years, τ1V˙O2 was not significantly different between sexes whatever age.

CONCLUSION

While age and lean body mass accounted for the sex-related differences of EPOC during childhood and adolescence, no significant effect of age and sex was observed on the V˙O2 recovery time constant after high-intensity exercise.

Anaerobic Contribution Determined in Free-Swimming: Sensitivity to Maturation Stages and Validity

Evaluation of anaerobic contribution is important under swimming settings (training and modification through ages), therefore, it is expected to change during maturation. The accumulated oxygen deficit (AOD) method can be used to determine the contribution of nonoxidative energy during swimming; however, it requires several days of evaluation. An alternative method to estimate anaerobic contribution evaluation (AC_ALT), which can also be evaluated without snorkel (i.e., free-swimming, AC_FS), has been proposed; however, these methods have never been compared. Thus, this study (i) analyzed the effect of maturation stage on AC_FS during maximal 400 m swimming (Part I), and (ii) compared AOD with AC_ALT and AC_FS, determined in a maximal 400 m effort (Part II). In Part I, 34 swimmers were divided into three groups, according to maturation stages (early-pubertal, middle-pubertal, and pubertal), and subjected to a maximal 400 m free-swimming to determine AC_FS. In Part II, six swimmers were subjected to one 400 m maximal effort, and four submaximal constant efforts. The AOD was determined by the difference between the estimated demand and accumulated oxygen during the entire effort. The AC_ALT and AC_FS (for Part I as well) was assumed as the sum of lactic and alactic anaerobic contributions. AC_FS was higher in pubertal (3.8 ± 1.1 L) than early (2.1 ± 0.9 L) and middle pubertal group (2.4 ± 1.1 L). No difference was observed among absolute AOD (3.2 ± 1.3 L), AC_ALT (3.2 ± 1.5 L), and AC_FS (4.0 ± 0.9 L) (F = 3.6; p = 0.06). Relative AOD (51.8 ± 12.2 mL·kg⁻¹), AC_ALT (50.5 ± 14.3 mL·kg⁻¹), and AC_FS (65.2 ± 8.8 mL·kg⁻¹) presented main effect (F = 4.49; p = 0.04), without posthoc difference. The bias of AOD vs. AC_ALT was 0.04 L, and AOD vs. AC_FS was −0.74 L. The limits of agreement between AOD and AC_ALT were +0.9 L and −0.8 L, and between AOD and AC_FS were +0.7 L and −2.7 L. It can be concluded that AC_FS determination is a feasible tool to determine anaerobic contribution in young swimmers, and it changes during maturation stages. Also, AC_FS might be useful to measure anaerobic contribution in swimmers, especially because it allows greater speeds.

Unobtrusive Estimation of Cardiorespiratory Fitness with Daily Activity in Healthy Young Men

Despite the importance of cardiorespiratory fitness, no practical method exists to estimate maximal oxygen consumption (VO₂max) without a specific exercise protocol. We developed an estimation model of VO₂max, using maximal activity energy expenditure (aEEmax) as a new feature to represent the level of physical activity. Electrocardiogram (ECG) and acceleration data were recorded for 4 days in 24 healthy young men, and reference VO₂max levels were measured using the maximal exercise test. aEE was calculated using the measured acceleration data and body weight, while heart rate (HR) was extracted from the ECG signal. aEEmax was obtained using linear regression, with aEE and HR as input parameters. The VO₂max was estimated from the aEEmax using multiple linear regression modeling in the training group (n = 16) and was verified in the test group (n = 8). High correlations between the estimated VO₂max and the measured VO₂max were identified in both groups, with a 15-hour recording being sufficient to produce a highly accurate VO₂max estimate. Additional recording time did not significantly improve the accuracy of the estimation. Our VO₂max estimation method provides a robust alternative to traditional approaches while only requiring minimal data acquisition time in daily life.

In-season changes in heart rate recovery are inversely related to time to exhaustion but not aerobic capacity in rowers

To determine if in-season changes in heart rate recovery (HRR) are related to aerobic fitness and performance in collegiate rowers. Twenty-two female collegiate rowers completed testing before and after their competitive season. Body fat percentage (BF%) was determined by dual-energy X-ray absorptiometry. Maximal aerobic capacity (VO_2max ) and time to exhaustion (T_max ) were determined during maximal rowing ergometer testing followed by 1 minute of recovery. HRR was expressed absolutely and as a percentage of maximal HR (HRR%_1 min ). Variables were compared using paired Wilcoxon tests. Multivariable regression models were used to predict in-season changes in HRR using changes in VO_2max and T_max , while accounting for changes in BF%. From preseason to post-season, VO_2max and BF% decreased (3.98±0.42 vs 3.78±0.35 L/min, P=.002 and 23.8±3.4 vs 21.3±3.9%, P<.001, respectively), while T_max increased (11.7±1.3 vs 12.6±1.3 min, P=.002), and HRR%_1 min increased (11.1±2.7 vs 13.8±3.8, P=.001). In-season changes in VO_2max were not associated with HRR%_1 min (P>.05). In-season changes in T_max were related to changes in HRR%_1 min (β=-1.67, P=.006). In-season changes in BF% were not related to changes in HRR (P>.05 for all). HRR_1 min and HRR%_1 min were faster preseason to post-season, although the changes were unrelated to VO_2max . Faster HRR%_1 min post-season was inversely related to changes in T_max . This suggests that HRR should not be used as a measure of aerobic capacity in collegiate rowers, but is a promising measure of training status in this population.

Short-Term Heart Rate Recovery is Related to Aerobic Fitness in Elite Intermittent Sport Athletes

Watson, AM, Brickson, SL, Prawda, ER, and Sanfilippo, JL. Short-term heart rate recovery is related to aerobic fitness in elite intermittent sport athletes. J Strength Cond Res 31(4): 1055-1061, 2017-Although heart rate recovery (HRR) has been suggested as a measure of fitness, minimal data exist among athletes. The purpose of this study was to determine if HRR is related to aerobic fitness in elite athletes and whether this relationship is influenced by sex or body composition. Eighty-four collegiate athletes (45 male athletes) underwent body fat percentage (BF%) determination by dual-energy x-ray absorptiometry and maximal treadmill testing followed by 5 minutes of recovery. V[Combining Dot Above]O2max and heart rate (HRmax) were determined, and HRR was calculated as a percentage of HRmax at 10 seconds, 30 seconds, and 1, 2, 3, 4, and 5 minutes after test completion. After stratifying by sex, participants were grouped as high fit or low fit based on V[Combining Dot Above]O2max median split. Heart rate recovery was compared between sexes and fitness level at each time point. Multivariable regression analysis was used to identify independent predictors of HRR using V[Combining Dot Above]O2max, BF%, and sex as covariates. Heart rate recovery did not differ significantly between sexes and was faster among high-fit participants at 10 and 30 seconds, but at no other time. V[Combining Dot Above]O2max was significantly correlated with HRR at 10 and 30 seconds (r = -0.34, p < 0.001 and r = -0.28, p = 0.008) only. After controlling for BF% and sex, V[Combining Dot Above]O2max remained significantly associated with HRR at 10 seconds (p = 0.007) but not at 30 seconds (p = 0.067) or any time thereafter. Aerobic capacity is related to faster HRR during the first 30 seconds only, suggesting that only very short term HRR should be used as a measure of aerobic fitness in intermittent sport athletes.

Obesity Modifies the Effect of Fitness on Heart Rate Indices during Exercise Stress Testing in Asymptomatic Individuals

<b><i>Objective:</i></b> To assess the impact of aerobic fitness on exercise heart rate (HR) indices in an asymptomatic cohort across different body mass index (BMI) categories. <b><i>Methods:</i></b> We performed a cross-sectional analysis of 506 working-class Brazilian subjects, free of known clinical cardiovascular disease (e.g. ischemic heart disease and stroke) who underwent an exercise stress test. <b><i>Results:</i></b> There was a significant trend towards decreased HR at peak exercise, HR recovery and chronotropic index (CI) measures as BMI increased, but resting HR increased significantly across BMI categories. In multivariate analysis, the change in CI per unit change in metabolic equivalents of task was greater among the obese subjects than the normal-weight (2.7 vs. -0.07; p interaction = 0.029) and overweight (2.7 vs. 0.7; p interaction = 0.044) subjects. A similar pattern was seen with peak HR and HR recovery, although the formal tests of interaction did not achieve statistical significance. <b><i>Conclusion:</i></b> Our findings strongly suggest that fitness is associated with a favorable HR profile and is modified by BMI. Intervention programs should place emphasis on fitness and not only on weight loss.

Effect of exercise intensity on post-exercise oxygen consumption and heart rate recovery

PURPOSE

There is some evidence that measures of acute post-exercise recovery are sensitive to the homeostatic stress of the preceding exercise and these measurements warrant further investigation as possible markers of training load. The current study investigated which of four different measures of metabolic and autonomic recovery was most sensitive to changes in exercise intensity.

METHODS

Thirty-eight moderately trained runners completed 20-min bouts of treadmill exercise at 60, 70 and 80% of maximal oxygen uptake (VO2max) and four different recovery measurements were determined: the magnitude of excess post-exercise oxygen consumption (EPOCMAG), the time constant of the oxygen consumption recovery curve (EPOCτ), heart rate recovery within 1 min (HRR60s) and the time constant of the heart rate recovery curve (HRRτ) .

RESULTS

Despite significant differences in exercise parameters at each exercise intensity, only EPOCMAG showed significantly slower recovery with each increase in exercise intensity at the group level and in the majority of individuals. EPOCτ was significantly slower at 70 and 80% of VO₂max vs. 60% VO₂max and HRRτ was only significantly slower when comparing the 80 vs. 60% VO₂max exercise bouts. In contrast, HRR60s reflected faster recovery at 70 and 80% of VO₂max than at 60% VO₂max.

CONCLUSION

Of the four recovery measurements investigated, EPOCMAG was the most sensitive to changes in exercise intensity and shows potential to reflect changes in the homeostatic stress of exercise at the group and individual level. Determining EPOCMAG may help to interpret the homeostatic stress of laboratory-based research trials or training sessions.

Interaction between dietary fat and exercise on excess postexercise oxygen consumption

The objective of this study was to determine the effect of increased physical activity on subsequent sleeping energy expenditure (SEE) measured in a whole room calorimeter under differing levels of dietary fat. We hypothesized that increased physical activity would increase SEE. Six healthy young men participated in a randomized, single-blind, crossover study. Subjects repeated an 8-day protocol under four conditions separated by at least 7 days. During each condition, subjects consumed an isoenergetic diet consisting of 37% fat, 15% protein, and 48% carbohydrate for the first 4 days, and for the following 4 days SEE and energy balance were measured in a respiration chamber. The first chamber day served as a baseline measurement, and for the remaining 3 days diet and activity were randomly assigned as high-fat/exercise, high-fat/sedentary, low-fat/exercise, or low-fat/sedentary. Energy balance was not different between conditions. When the dietary fat was increased to 50%, SEE increased by 7.4% during exercise (P < 0.05) relative to being sedentary (baseline day), but SEE did not increase with exercise when fat was lowered to 20%. SEE did not change when dietary fat was manipulated under sedentary conditions. Physical activity causes an increase in SEE when dietary fat is high (50%) but not when dietary fat is low (20%). Dietary fat content influences the impact of postexercise-induced increases in SEE. This finding may help explain the conflicting data regarding the effect of exercise on energy expenditure.

Relationship between post-exercise heart rate variability and skinfold thickness

This investigation aimed to determine if groupings based upon sum of skinfold thickness (SF) would reflect the differences in heart rate variability (HRV) measured for up to 30-minutes following maximal exercise, and to determine the extent in variation in post-exercise HRV that could be accounted for between the following independent variables: SF, body mass index (BMI) and maximal oxygen consumption (VO2max). SF and BMI measurements were performed on fifty-four men who completed maximal exercise testing to determine VO2max. HRV was evaluated for five-minutes before (Pre), at 0-5 minutes post- (Post1) and 25-30 minutes post-exercise (Post2), and analyzed by frequency domain [high frequency (HF) power, and HF to low frequency power ratio (LF:HF)). Two groups were formed based on being above or below the sample mean value of SF. HF and LF:HF were significantly higher and lower, respectively, at Pre and Post 2 in Group 1 compared to Group 2 (p < 0.05), which remained after controlling for VO2max and BMI. Furthermore, there was a significant trend toward baseline in post-exercise HRV in Group 1 (p < 0.05) but not in Group 2 (p > 0.05). In addition, SF was the only variable to significantly relate to the post-exercise HRV parameters (p < 0.05). The findings of this investigation suggest greater SF is related to a delayed return of HRV toward baseline from maximal exercise. The association between SF and HRV is independent of VO2max and BMI.