Effects of high-intensity interval training on cardiometabolic risk factors in overweight/obese women

The purpose of this study was to evaluate two practical interval training protocols on cardiorespiratory fitness, lipids and body composition in overweight/obese women. Thirty women (mean ± SD; weight: 88.1 ± 15.9 kg; BMI: 32.0 ± 6.0 kg · m²) were randomly assigned to ten 1-min high-intensity intervals (90%VO₂ peak, 1 min recovery) or five 2-min high-intensity intervals (80–100% VO₂ peak, 1 min recovery) or control. Peak oxygen uptake (VO₂ peak), peak power output (PPO), body composition and fasting blood lipids were evaluated before and after 3 weeks of training, completed 3 days per week. Results from ANCOVA analyses demonstrated no significant training group differences for any primary variables (P > 0.05). When training groups were collapsed, 1MIN and 2MIN resulted in a significant increase in PPO (?18.9 ± 8.5 watts; P = 0.014) and time to exhaustion (?55.1 ± 16.4 s; P = 0.001); non-significant increase in VO₂ peak (?2.36 ± 1.34 ml · kg^?1 · min^?1; P = 0.185); and a significant decrease in fat mass (FM) (??1.96 ± 0.99 kg; P = 0.011). Short-term interval exercise training may be effective for decreasing FM and improving exercise tolerance in overweight and obese women.     

Recovery Responses to Maximal Exercise in Healthy-Weight Children and Children With Obesity

Purpose: The purpose of this study was to examine differences in heart rate recovery (HRRec) and oxygen consumption recovery (VO₂ recovery) between young healthy-weight children and children with obesity following a maximal volitional graded exercise test (GXTmax). Method: Twenty healthy-weight children and 13 children with obesity completed body composition testing and performed a GXTmax. Immediately after the GXTmax, HRRec and VO₂ recovery were measured each minute for 5 consecutive minutes. Results: There were no statistically significant group differences in HRRec for the 5 min following maximal exercise, Wilks’s Lambda = .885, F(4, 28) = 0.911, p = .471, between the healthy-weight children and children with obesity despite statistically significant differences in body fat percentage (BF%; healthy-weight children, 18.5 ± 6.1%; children with obesity, 41.1 ± 6.9%, p < .001) and aerobic capacity relative to body mass (VO₂ peak; healthy-weight children, 46.8 ± 8.2 mL/kg/min; children with obesity, 31.9 ± 4.7 mL/kg/min, p < .001). There were statistically significant differences in VO₂ recovery for the 5 min following exercise, Wilks’s Lambda = .676, F(4, 26) = 3.117, p = .032. There were no statistically significant correlations between HRRec and body mass index (BMI), BF%, VO₂peak, or physical activity. Conclusions: In a healthy pediatric population, obesity alone does not seem to significantly impact HRRec, and because HRRec was not related to obesity status, BMI, or BF%, it should not be used as the sole indicator of aerobic capacity or health status in children. Using more than one recovery variable (i.e., HRRec and VO₂ recovery) may provide greater insight into cardiorespiratory fitness in this population.     

Heart rate prescribed walking training improves cardiorespiratory fitness but not glycaemic control in people with type 2 diabetes

Abstract

In this study, we examined the effects of a supervised, heart rate intensity prescribed walking training programme on cardiorespiratory fitness and glycaemic control in people with type 2 diabetes mellitus. After receiving local ethics approval, 27 individuals (21 males, 6 females) with type 2 diabetes were randomly assigned to an experimental (“walking”) or control group. Participants completed a Balke-Ware test to determine peak heart rate, peak oxygen consumption ([Vdot]O_2peak), and peak gradient. The walking group then completed a 7-week (four sessions a week) supervised, heart rate prescribed walking training programme, whereas the control group continued daily life. After training, participants completed another Balke-Ware test. Fasting blood glucose and glycosylated haemoglobin were measured at rest. The results showed that walking training elicited 80% (s = 2) of peak heart rate and a rating of perceived exertion of 11 (s = 1). Peak heart rate and [Vdot]O_2peak were higher in the walking than in the control group after training (P < 0.05). Based on the peak gradient before training, the respiratory exchange ratio was significantly lower (P < 0.05) and there was a strong trend for [Vdot]O₂ (P = 0.09) and heart rate (P = 0.09) to be lower after training at the same gradient in the walking compared with the control group. These improvements increased walking peak gradient by 5 min (s = 4 min) compared with the control (P < 0.05). There was no change in fasting blood glucose or glycosylated haemoglobin after training. Despite no change in glycaemic control, heart rate prescribed walking improved peak and sub-maximal cardiorespiratory responses. The beneficial adaptations support the use of heart rate monitoring during walking in people with type 2 diabetes mellitus.     

Comparison of visual,automatic and semiautomatic methods to determine ventilatory indices in 50 to 60 years old adults

ABSTRACT

The aim of this study was to compare different methods of detecting ventilatory indices (VI) and to investigate the impact of cardiorespiratory fitness (CRF) level on VI detection. Fifty females and fifty males completed a graded exercise test until volitional exhaustion with continuous gas-exchange measurement. The first and second ventilatory indices (VI-1, VI-2) were detected through different single automatic methods and through a semiautomatic method which combines visual and automatic detection methods. Additionally, the VIs were detected visually by two experts which served as the study specific gold standard. When comparing the semiautomatic method at VI-1 (intraclass correlation coefficients (ICC) 0.88 [0.81, 0.92], Bland-Altman bias ± limits of agreement (LoA) 55 ± 334 ml O₂ · min^?1) and VI-2 (ICC 0.97 [0.96, 0.98], LoA 1 ± 268 ml O₂ · min^?1) to the visually detected VI, high levels of agreements and no significant differences were found. This was not the case for any of the other automatic methods. Additionally, we couldn’t find any relevant differences regarding the CRF level.

We therefore concluded that the semiautomatic detection method should be used for VI detection, as results are more accurate than in any of the single-automatic methods.

Abbreviations: CPET: cardiopulmonary exercise test; CRF: Cardiorespiratory fitness; VO_2peak: peak oxygen uptake; VI-1: first ventilatory indices; VI-2: second ventilatory indices; LoA: Bland-Altman bias ± limits of agreement; ICC: intraclass correlation coefficient.     

Effects of aerobic exercise and cognitively engaging exercise on cardiorespiratory fitness and motor skills in primary school children: A cluster randomized controlled trial

ABSTRACT

This paper examined effects of two interventions on cardiorespiratory fitness and motor skills, and whether these effects are influenced by baseline levels, and dose of moderate-to-vigorous physical activity (MVPA) during the intervention. A cluster randomized controlled trial was implemented in 22 schools (n = 891; 9.2 ± 07 years). Intervention groups received aerobic or cognitively engaging exercise (14-weeks, four lessons per week). Control groups followed their regular physical education programme. Cardiorespiratory fitness, motor skills and MVPA were assessed. Multilevel analysis showed no main effects on cardiorespiratory fitness and motor skills although the amount of MVPA was higher in the aerobic than in the cognitively engaging and control group. Intervention effects did not depend on baseline cardiorespiratory fitness and motor skills. Children with a higher dose of MVPA within the intervention groups had better cardiorespiratory fitness after both interventions and better motor skills after the cognitively engaging intervention. In conclusion, the interventions were not effective to enhance cardiorespiratory fitness and motor skills at a group level, possibly due to large individual differences and to a total dose of MVPA too low to find effects. However, the amount of MVPA is an important factor that influence the effectiveness of interventions.     

The Importance of Adolescents’ Participation in Organized Sport According to VO2peak: A Longitudinal Study

Research from several countries has documented a decline in physical activity (PA) levels and in participation in organized sport with increasing age, indicating that organized sport may be of importance to adolescents’ cardiorespiratory fitness (CRF). Purpose: The purpose of this study was to examine how regular participation in organized and unorganized PA affected the development of adolescents’ CRF (peak oxygen consumption [VO₂peak]), when controlled for sex interaction. Method: Data on direct measures of VO₂peak and participation in organized PA among adolescents organized into 3 groups (participation in organized sport, participation in unorganized PA, and no weekly PA) were collected from 76 students (39 boys and 37 girls), when they were aged 14 and 19 years old. Results: Statistically significant differences were found between VO₂peak values in the 3 groups at both 14 years of age, F(2, 73) = 7.16, p < .05, ?² = .170, and 19 years of age, F(2, 73) = 14.00, p < .05, ?² = .300, independent of sex at both 14 and 19 years of age, F(2, 73) = 0.05, p > .05, ?² = .02, and F(2, 73) = 0.05, p > .05, ?² = .00. Adolescents participating in organized sport also had statistically significantly higher VO₂peak values than adolescents participating in unorganized PA and those with no weekly PA, at both 14 and 19 years of age. Conclusion: From a health perspective, in terms of CRF, the findings highlight the importance of encouraging adolescents to participate in organized sport and to refrain from dropping out of organized sport programs.     

Determination of peak cardiorespiratory fitness parameters in children: which averaging method should we use?

The purpose of this study was to identify which averaging methods most accurately measures peak cardiorespiratory fitness (CRF) parameters [peak O₂ uptake (VO₂), peak O₂pulse and peak respiratory exchange ratio (RER)] in a sample of healthy children and adolescents. In this cross-sectional multicenter study, we recruited 278 healthy children aged 12–17 years. We compared the mean peak value of three CRF parameters using the recommended averaging methods (30-second block average) with alternative averaging methods such as moving averages or shorter smoothing periods. We also assessed averaging methods for accuracy by individually reviewing breath-by-breath scatter plots. The 30-second block average method resulted in a lower mean peak VO₂ and in an increased proportion of underestimated peak values. Using a 30-second moving average significantly increased mean peak values which increased accuracy. Similar results were found for peak RER and peak O₂pulse. In conclusion, the currently recommended averaging method (30-second block average) increased the risk of misinterpretation of peak CRF values in children. Using a moving average approach decreased misinterpretation and increased accuracy.     

Effects of 12 weeks of combined training without caloric restriction on inflammatory markers in overweight girls

The objective of the present study was to investigate the effects of combined training without caloric restriction on inflammatory markers in overweight girls. Thirty-three girls (13–17 years) were assigned into overweight training (n = 17) or overweight control (n = 16) groups. Additionally, a normal-weight group (n = 15) was used as control for the baseline values. The combined training programme consisted of six resistance exercises (three sets of 6–10 repetitions at 60–70% 1 RM) followed by 30 min of aerobic exercise (walking/running) at 50–80% VO_2peak, performed in the same 60 min session, 3 days/weeks, for 12 weeks. Body composition, dietary intake, aerobic fitness (VO_2peak), muscular strength (1 RM), glycaemia, insulinemia, lipid profile and inflammatory markers (C-reactive protein, interleukin-6, tumour necrosis factor-alpha, interleukin-10, leptin, resistin and adiponectin) were measured before and after intervention. There was a significant decrease in body fat (P < 0.01) and increase in fat-free mass (P < 0.01), VO_2peak (P < 0.01), 1 RM for leg press (P < 0.01) and bench press (P < 0.01) in the overweight training group. Concomitantly, this group presented significant decreases in serum concentrations of C-reactive protein (P < 0.05) and leptin (P < 0.05), as well as in insulin resistance (P < 0.05) after the experimental period. In conclusion, 12 weeks of combined training without caloric restriction reduced inflammatory markers associated with obesity in overweight girls.     

Effects of an acute bout of exercise on serum soluble leptin receptor (sOB-R) levels

Abstract

We investigated the effects of an acute bout of exercise on serum soluble leptin receptor (sOB-R) concentrations. Eighteen male participants completed two different exercise sessions with intensities of 25% and 65% maximal aerobic capacity (VO₂max). In addition to the energy expenditure during exercise sessions being measured, blood samples were collected before exercise, and immediately, at 24 h, and at 48 h post-exercise to analyse sOB-R, leptin and insulin levels. At 24 h post-exercise, sOB-R and leptin concentrations at the 65% VO₂max were significantly different from those at the 25% VO₂max. Leptin levels at 48 h post-exercise were also significantly lower for the 65% VO₂max than for the 25% VO₂max (P < 0.01). In the 65% VO₂max session, the energy expenditure during exercise was significantly associated with leptin concentrations at 24 h and 48 h and sOB-R concentrations at 24 h post-exercise. However, no correlations were found between sOB-R and leptin at the three post-exercise time points. In conclusion, an acute bout of exercise with 920 kcal of output resulted in an increase in sOB-R levels at 24 h post-exercise. However, the changes in sOB-R levels due to an acute bout of exercise might not contribute to the delayed decrease observed for leptin.     

Isolated Obesity Is Not Enough to Impair Cardiac Autonomic Modulation in Metabolically Healthy Men

Purpose: To evaluate whether excess body mass influences the heart rate variability (HRV) indexes at rest, and to correlate adiposity indicators and the aerobic fitness with cardiac autonomic variables in metabolically healthy young adults. Method: In all, 41 untrained males (M_age = 21.80, SD = 2.14 years), 14 normal weight (M_BMI = 22.28, SD = 1.86 kg?m^?2), 11 overweight (M_BMI = 26.95, SD = 1.43 kg?m^?2), and 16 obese (M_BMI = 33.58, SD = 3.06 kg?m^?2) metabolically healthy (normal values of blood pressure, fasting blood glucose, triglycerides, and total cholesterol), underwent evaluations of the HRV at rest and of the peak oxygen consumption (VO₂ peak) during maximal exercise on a cycle ergometer. Results: Blood pressure, heart rate, HRV indexes, casual blood glucose, oxidative stress, and antioxidant activity did not differ among the groups. The VO₂ peak (mL?kg^?1?min^?1) was lower in the obese group compared with the normal weight and overweight groups. The body mass (r = ?.40 to ?.45) and abdominal circumference (r = ?.39 to ?.52) were slightly to moderately correlated with SD1, SD2, RMSSD, SDNN, pNN50, LF, and HF indexes and total power. The VO₂ peak (mL?kg^?1?min^?1) was slightly to moderately correlated (r = .48 to .51) with SD2, SDNN, and LF indexes in the individuals with excess body mass. Conclusion: Cardiac autonomic modulation at rest was preserved in metabolically healthy obese young men. However, the indicators of adiposity, as well as the aerobic fitness were correlated with cardiac autonomic modulation in the individuals with excess body mass.     

Associations of accelerometer-measured sedentary time,sedentary bouts,and physical activity with adiposity and fitness in children

ABSTRACT

Sedentary time (ST) has been inconsistently associated with adiposity and cardiorespiratory fitness in children in previous studies. We studied cross-sectional associations of ST, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) with fat mass index (FMI) and cardiorespiratory fitness (estimated VO₂max). Associations were evaluated with and without considering pattern of ST by bout length. We measured ST and activity by a wrist-worn accelerometer, FMI by bioelectrical impedance, and VO₂max by Pacer test in 443 children (51.2% girls, 10.2 ± 0.6 years). Isotemporal substitution regression models estimated the effects of substituting ST, LPA, and MVPA on FMI and VO₂max. Further models repeated analyses separating ST into short (<10 min) and long (≥10 min) bouts. Only replacing ST or LPA with MVPA was consistently associated with lower FMI and greater VO₂max. When separated by bout length, only one unique association was found where replacing long ST bouts with short ST bouts was associated with lower FMI in girls only. In conclusion, activity pattern is associated with adiposity in girls and fitness in boys and girls. Separating ST into long and short ST bouts may be of minimal importance when assessing associations with adiposity and fitness using wrist-worn accelerometry in children.     

Four weeks of running sprint interval training improves cardiorespiratory fitness in young and middle-aged adults

The purpose of this study was to determine the effectiveness of a 4-week running sprint interval training protocol to improve both aerobic and anaerobic fitness in middle-aged adults (40–50 years) as well as compare the adaptations to younger adults (20–30 years). Twenty-eight inactive participants – 14 young 20–30-year-olds (n = 7 males) and 14 middle-aged 40–50-year-olds (n = 5 males) – completed 4 weeks of running sprint interval training (4 to 6, 30-s “all-out” sprints on a curved, self-propelled treadmill separated by 4 min active recovery performed 3 times per week). Before and after training, all participants were assessed for maximal oxygen consumption (VO_2max), 2000 m time trial performance, and anaerobic performance on a single 30-s sprint. There were no interactions between group and time for any tested variable, although training improved relative VO_2max (young = 3.9, middle-aged = 5.2%; P < 0.04), time trial performance (young = 5.9, middle-aged = 8.2%; P < 0.001), peak sprint speed (young = 9.3, middle-aged = 2.2%; P < 0.001), and average sprint speed (young = 6.8, middle-aged = 11.6%; P < 0.001) in both young and middle-aged groups from pre- to post-training on the 30-s sprint test. The current study demonstrates that a 4-week running sprint interval training programme is equally effective at improving aerobic and anaerobic fitness in younger and middle-aged adults.     

Aerobic fitness and physical activity are inversely associated with body fat,dyslipidemia and inflammatory mediators in children and adolescents living with HIV

This study aimed to investigate if moderate to vigorous physical activity (MVPA) and aerobic fitness are associated with cardiovascular risk factors in HIV+ children and adolescents. Sixty-five children and adolescents (8 to 15 years) provided minutes of MVPA measured by accelerometers and peak oxygen uptake (peak VO₂) by breath-by-breath respiratory exchange. Cardiovascular risk factors were characterized by body fat, blood pressure, total cholesterol, HDL-c, LDL-c, triglycerides, glucose, insulin, C-reactive protein (CRP), interleukin (IL)-6, tumor necrosis factor-alpha (TNF-α) and carotid intima-media thickness. Results indicated that higher MVPA was associated with lower values of total (β = ?3.566) and trunk body fat (β = ?3.495), total cholesterol (β = ?0.112) and LDL-c (β = ?0.830). Likewise, higher peak VO₂ was associated with lower total (β = ?0.629) and trunk body fat values (β = ?0.592) and levels of CRP (β = ?0.059). The physically active participants had lower total cholesterol (?24.4 mg.dL^?1) and LDL-c (?20.1 mg.dL^?1) compared to participants judged to be insufficiently active. Moreover, participants with satisfactory peak VO? showed lower total (?4.1%) and trunk (?4.3%) body fat, CRP (?2.3 mg.L^?1), IL-6 (?2.4 pg.mL^?1) and TNF-α (?1.0 pg.mL^?1) compared to low peak VO₂ peers. High levels of MVPA and aerobic fitness may prevent developing of cardiovascular risk factors in children and adolescents HIV+.     

Effects of high-intensity interval training on canoeing performance

The purpose of this study was to compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) utilizing a canoeing ergometer on endurance determinants, as well as aerobic and anaerobic performances among flat-water canoeists. Fourteen well-trained male flat-water canoeists were divided into an HIIT group or an MICT group. All subjects performed a continuous graded exercise test (GXT) and three fixed-distance (200, 500, and 1000?m) performance tests on a canoeing ergometer to determine canoeing economy, peak oxygen uptake (VO₂peak), and power at VO₂peak, and to calculate the critical velocity (CV) and anaerobic work capacity before and after the training programmes. The training programme involved training on a canoeing ergometer three times per week for four weeks. HIIT consisted of seven 2 min canoeing bouts at an intensity of 90% VO₂peak separated by 1 min of rest. The MICT group was trained at an intensity of 65% VO₂peak continuously for 20 min. After four weeks of training, performance in the 200-m distance test and the power at VO₂peak significantly improved in the HIIT group; performance in the 500?m and 1000?m distances and CV significantly improved in the MICT group. However, all variables were not significantly different between groups. It is concluded that HIIT for four weeks is an effective training strategy for improvement of short-distance canoeing performance. In contrast, MICT improves middle-distance canoeing performances and aerobic capacity.     

Transient VO2 Characteristics in Children at the Onset of Steady-Rate Exercise

Abstract

The transient oxygen uptake (VO₂) response during the initial phase of exercise was investigated in 28 children (mean age ± SD = 10.2 ± 2.28 years) during constant load submaximum bicycle ergometer exercise (mean power output ± SD = 56 ± 4.0 watts; mean VO₂ ± SD = .92 ± .141 [mdot] min^-1). The VO₂ half-time (VO₂ - t½) averaged (± SD) 34.8 (± 12.70) sec which is similar to that observed in adults. Examination of the VO₂-t ½ response as it related to age (7 to 14 years) showed that younger children attained steady-rate VO₂ more quickly than older children (r = .77 between age and VO₂-t½, P < .05). Body size, maturational level, exercise intensity, cardiorespiratory factors, and anaerobic potential are suggested as possible factors accounting for the positive age vs VO₂-t ½ relationship.     

Effects of two physical education programmes on health- and skill-related physical fitness of Albanian children

This study aims to evaluate the effectiveness of two school-based physical education (PE) programmes (exercise-based and games-based) compared with traditional PE, on health- and skill-related physical fitness components in children in Tirana, Albania.

Participants were 378 first-grade (6.8 years) and 389 fourth-grade (9.8 years) children attending four randomly selected schools in Tirana. Twenty-four school classes within these schools were randomly selected (stratified by school and school grade) to participate as exercise group (EG), games group (GG) and control group (CG). Both EG and GG intervention programmes were taught by professional PE teachers using station/circuit teaching framework while CG referred to traditional PE school lessons by a general teacher. All programmes ran in parallel and lasted 5 months, having the same frequency (twice weekly) and duration (45 min). Heart rate (HR) monitoring showed that intensity during PE lessons was significantly higher in the intervention groups compared with control (P < 0.001). Both PE exercise- and games programmes significantly improved several health- and skill-related fitness indicators compared with traditional PE lessons (e.g. gross motor skill summary score: 9.4 (95% CI 7.9; 10.9) for exercise vs. control and 6.5 (95% CI 5.1; 8.1) for games vs. control, cardiorespiratory fitness: 2.0 ml O₂ · min^?1 · kg^?1 (95% CI 1.5; 2.4) for exercise vs. control and 1.4 ml O₂ · min^?1 · kg^?1 (95% CI 1.0; 1.8) for games vs. control). Furthermore, compared to games-based PE, exercise-based PE showed more positive changes in some gross motor coordination skills outcomes, coordination skills outcomes and cardiorespiratory fitness. The results from this study show that exercise- and games-based PE represents a useful strategy for improving health- and skill-related physical fitness in Albanian elementary school children. In addition, the study shows that exercise-based PE was more effective than games-based PE in improving gross motor function and cardiorespiratory fitness.     

Matching of Male and Female Subjects Using VO2 max

Abstract

We compared cardiorespiratory responses to exercise on an underwater treadmill (UTM) and land treadmill (LTM) and derived an equation to estimate oxygen consumption (VO₂) during UTM exercise. Fifty-five men and women completed one LTM and five UTM exercise sessions on separate days. The UTM sessions consisted of chest-deep immersion, with 0, 25, 50, 75, and 100% water-jet resistance. All session treadmill velocities increased every 3 min from 53.6 to 187.8 m·min^-1. Cardiorespiratory responses were similar between LTM and UTM when jet resistance for UTM was ≥ 50%. Using multiple regression analysis, weight-relative VO₂ could be estimated as: VO₂ (mLO₂·kg^-1·min^-1) = 0.19248 · height (cm) + 0.17422 · jet resistance (% max) + 0.14092 · velocity (m·min^-1) - 0.12794 · weight (kg) - 27.82849, R²= .82. Our data indicate that similar LTM and UTM cardiorespiratory responses are achievable, and we provide a reasonable estimate of UTM VO₂.     

Development of 1-mile walk tests to estimate aerobic fitness in children

To examine the reliability and validity of 1-mile walk tests for estimation of aerobic fitness (VO_2max) in 10- to 13-year-old children and to cross-validate previously published equations. Participants (n = 61) walked 1-mile on two different days. Self-reported physical activity, demographic variables, and aerobic fitness were used in multiple regression analyses. Eight models were developed with various combinations of predictors. The recommended model for fitness testing in schools was: VO_2max = 120.702 + (4.114 × Sex [F = 0, M = 1]) – (2.918 × 1-mile Walk Time [min]) – (2.841 × Age), R = .73, standard error of estimate = 6.36 mL·kg^?1·min^?1. Cross-validation of previously published equations demonstrated lower correlations with measured VO_2max than the newly developed walk tests. Evidence of reliability and validity for 1-mile walk tests to estimate VO_2max in young children was provided. The model that included 1-mile walk time, age, and sex may be appropriate for youth fitness testing in physical education, particularly for unmotivated or overweight young children.