Changes in Cardiorespiratory Fitness Following Exercise Training Prescribed Relative to Traditional Intensity Anchors and Physiological Thresholds: A Systematic Review with Meta-analysis of Individual Participant Data

BACKGROUND

It is unknown whether there are differences in maximal oxygen uptake ( V O2max) response when prescribing intensity relative to traditional (TRAD) anchors or to physiological thresholds (THR).

OBJECTIVES

The present meta-analysis sought to compare: (a) mean change in V O2max, (b) proportion of individuals increasing V O2max beyond a minimum important difference (MID) and (c) response variability in V O2max between TRAD and THR.

METHODS

Electronic databases were searched, yielding data for 1544 individuals from 42 studies. Two datasets were created, comprising studies with a control group ('controlled' studies), and without a control group ('non-controlled' studies). A Bayesian approach with multi-level distributional models was used to separately analyse V O2max change scores from the two datasets and inferences were made using Bayes factors (BF). The MID was predefined as one metabolic equivalent (MET; 3.5 mL kg-1 min-1).

RESULTS

In controlled studies, mean V O2max change was greater in the THR group compared with TRAD (4.1 versus 1.8 mL kg-1 min-1, BF > 100), with 64% of individuals in the THR group experiencing an increase in V O2max > MID, compared with 16% of individuals taking part in TRAD. Evidence indicated no difference in standard deviation of change between THR and TRAD (1.5 versus 1.7 mL kg-1 min-1, BF = 0.55), and greater variation in exercise groups relative to non-exercising controls (1.9 versus 1.3 mL kg-1 min-1, BF = 12.4). In non-controlled studies, mean V O2max change was greater in the THR group versus the TRAD group (4.4 versus 3.4 mL kg-1 min-1, BF = 35.1), with no difference in standard deviation of change (3.0 versus 3.2 mL kg-1 min-1, BF = 0.41).

CONCLUSION

Prescribing exercise intensity using THR approaches elicited superior mean changes in V O2max and increased the likelihood of increasing V O2max beyond the MID compared with TRAD. Researchers designing future exercise training studies should thus consider the use of THR approaches to prescribe exercise intensity where possible. Analysis comparing interventions with controls suggested the existence of intervention response heterogeneity; however, evidence was not obtained for a difference in response variability between THR and TRAD. Future primary research should be conducted with adequate power to investigate the scope of inter-individual differences in V O2max trainability, and if meaningful, the causative factors.

Effect of short moderate intensity exercise bouts on cardiovascular function and maximal oxygen consumption in sedentary older adults

AIM

To investigate effect of <10 min moderate intensity exercise on cardiovascular function and maximal oxygen consumption (V ˙ O2max) among sedentary adults.

METHODS

We studied 53 sedentary urbanites aged ≥50 years, randomised into: (1) male (MS) and (2) female (FS) undertaking three short-duration exercise (5-10 min) daily, and (3) male (ML) and (4) female (FL) exercising 30-60 min 3-5 days weekly. Resting systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate andV ˙ O2max were measured at baseline and 8 weekly for 24 weeks.

RESULTS

At baseline, 50% MS, 61.5% ML, 53.8% FS and 53.8% FL had SBP ≥120 mm Hg, and 14.3% MS, 53.8% ML, 23.1% FS and 38.5% FL had DBP ≥80 mm Hg. At 24 weeks, where SBP remained ≥120 mm Hg, values decreased from 147±19.2 to 132.3±9.6 mm Hg (50% of MS), from 144±12.3 to 128±7.0 mm Hg (23.1% of ML), from 143.1±9.6 to 128.0±7.0 mm Hg (53.8% of FS) and from 152.3±23.7 to 129±3.7 mm Hg (30.8% of FL). For DBP ≥80 mm Hg, MS and FS percentages maintained, but values decreased from 101±15.6 to 84.5±0.7 mm Hg (MS) and 99.0±3.6 to 87.7±4.9 mm Hg (FS). In ML and FL, percentage with DBP ≥80 mm Hg dropped to 15.4% (86.1±6.5 to 82.5±3.5 mm Hg) and (91.4±5.3 to 83.5±0.71 mm Hg).V ˙ O2max increased from 26.1±4.4 to 32.0±6.2 for MS, from 25.8±5.1 to 28.8±5.4 for ML (group differences p=0.02), from 20.2±1.8 to 22.7±2.0 for FS and from 21.2±1.9 to 24.2±2.7 for FL (groups differences p=0.38).

CONCLUSION

Accumulated moderate intensity exercise bouts of <10 min confer similar-to-better cardiovascular andV ˙ O2max improvements compared with current recommendations among sedentary adults.

The Roles of Menopausal-specific Quality of Life on Breast Cancer Screening Beliefs in Menopausal and Postmenopausal Women

Objectives

This study investigated the association between menopausal-specific quality of life (MENQOL) and breast cancer screening beliefs among Hong Kong Chinese menopausal and postmenopausal women.

Methods

A cross-sectional study was employed to collect data. The questionnaire was distributed to a convenience sample of 218 women aged above 45. The outcome variables were breast cancer screening beliefs and breast examination. Multiple regression analyses were conducted to test the effect of 4 domains in MENQOL (vasomotor, psycho-social, physical, and sexual symptom) and the health behaviors on the 2 outcome variables.

Results

This study found that the overall MENQOL scores (in particular psycho-social, and physical aspects) were significantly associated with positive attitudes toward health check-ups and better knowledge and perceptions in breast cancer. Regular exercise was also significantly related to breast examination.

Conclusions

MENQOL (especially psycho-social and physical domain) and regular exercise are important factors associated with breast cancer screening beliefs. The results of this study illuminate health care professionals to develop primary health care strategies to improve the quality of life of mid-life women.

Effects of Exercise Training on Fat Loss and Lean Mass Gain in Mexican-American and Korean Premenopausal Women

We investigated the effect of exercise training on body composition change in women. Nineteen Mexican-American and 18 Korean premenopausal overweight/obese women were randomized into one of the following groups: control, low-intensity training group (LI), and high-intensity training group (HI). Subjects completed 12 weeks of training at 50-56% maximal oxygen consumption (LI) or 65-70% maximal oxygen consumption (HI). Body composition components were measured at baseline and after training using dual-energy X-ray absorptiometry for Mexican-Americans, while whole-body composition was measured by the direct segmental multifrequency bioelectrical impedance analysis and abdominal fat was measured by single-slice computed tomography for Koreans. Data were analyzed using mixed-model repeated measures independent of age, ethnicity, and body mass index (BMI). Exercise training showed a significant effect on BMI, fat percentage, fat mass, lean mass, and visceral adipose tissue area. HI significantly decreased fat mass and fat percentage but increased lean mass (all P < 0.05). LI significantly reduced BMI, fat mass, fat percentage, and visceral adipose tissue area but increased lean mass (all P < 0.05). Exercise training had a beneficial effect on reducing BMI, fat percentage, fat mass, and visceral adipose tissue area but had no effect on increasing lean mass for Mexican-American and Korean premenopausal overweight/obese women.

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.

Physical activity recommendations and cardiovascular disease risk factors in young Hispanic women

Despite the benefits associated with regular physical activity, there is little epidemiological evidence to support positive health outcomes when meeting physical activity guidelines in high-risk ethnic groups, such as Hispanic women. We compared cardiovascular disease risk factors between young Hispanic women who meet and those who do not meet current physical activity guidelines. Height, weight, waist circumference, and blood pressure were measured in 60 Hispanic women aged 20-39 years. Lipids, C-reactive protein, insulin, and glucose were assessed. Body composition and cardiovascular fitness were assessed by BodPod and maximal oxygen uptake (VO₂(max)) respectively. Participants wore an accelerometer and average minutes (assessed in 10-min bouts) spent in light, moderate, and hard daily activity for weekdays and weekends was determined. Seventy percent of participants did not meet the recommended physical activity guidelines, whereas 30% did so. Following current physical activity guidelines was associated with significantly lower mean cholesterol (mean ± s: 4.2 ± 0.8 vs. 4.7 ± 0.9 mmol · l⁻¹) and triglycerides (0.7 ± 0.3 vs. 1.1 ± 0.6 mmol · l⁻¹), and higher fat-free mass (43.3 ± 3.8 vs. 40.2 ± 5.1 kg) and relative (40.4 ± 7.6 vs. 35.6 ± 7.0 ml · kg⁻¹ · min⁻¹) and absolute (2.5 ± 0.3 vs. 2.1 ± 0.4 litres · min⁻¹) VO₂(max) (P < 0.05). These findings suggest an improved health status in women who meet versus those who did not meet current physical activity guidelines.

Dose-response relationship between moderate-intensity exercise duration and coronary heart disease risk factors in postmenopausal women

PURPOSE

This study was designed to investigate whether, in a dose-response manner, there would be greater health benefits in a group of postmenopausal women completing 45 minute- vs. 30 minutes of moderate intensity (50% maximal oxygen uptake reserve, VO2R) exercise 5 days . wk(-1).

METHODS

Apparently healthy but sedentary postmenopausal women (n = 33) were randomized to a nonexercise control group, a 30-minute exercise duration group, or a 45-minute exercise duration group. Exercise training was performed 5 days . wk(-1) for 12 weeks at 50% VO2R. Participants were instructed to not change their usual diet throughout the study.

RESULTS

Twenty-six women completed the study. After 12 weeks, VO2max increased significantly (p < 0.05) in both 30-minute (0.20 +/- 0.21 L . min(-1)) and 45-minute (0.41 +/- 0.10 L . min(-1)) groups. Repeated measures ANOVA identified a significant interaction between exercise duration and VO2max values (F = 4.72, p < 0.05), indicating that VO2max responded differently to 30-minute and 45-minute exercise durations. Trend analysis showed that body mass, body composition, waist circumference, and high-density lipoprotein cholesterol (HDL-C) changed favorably (p < 0.05) across control, 30-minute, and 45-minute groups.

CONCLUSIONS

Although most health organizations agree that 150 min . wk(-1) of physical activity will reduce the risk of all-cause and cardiovascular mortality, few randomized, controlled studies have examined whether completing more physical activity than the recommended amount will yield additional benefits. Findings from the present study suggest that there is a dose-response relationship between exercise duration and numerous health outcomes in postmenopausal women, including cardiorespiratory fitness, body mass, body composition, waist circumference, and HDL-C.