The validity of non-exercise cardiorespiratory fitness prediction models

Experimental effects of acute exercise duration and exercise recovery on mood state

OBJECTIVE

Accumulating evidence suggests that, in addition to various psychosocial parameters, affective responses to exercise play an important role in subserving future exercise behavior. This study comprehensively evaluated whether acute exercise duration and recovery period influenced the relationship between moderate-intensity walking exercise and mood profile.

METHOD

We employed a randomized controlled cross-over trial. Participants completed two laboratory visits, separated by one-week. One of the visits involved a mood profile assessment with no exercise, while the other visit involved a mood profile assessment after an acute bout of exercise. Participants (N = 352; 22 per group; young [M_age = 21 yrs] healthy adults) were randomized into one of 16 experimental groups: 10, 20, 30, 45 or 60min bout of exercise coupled with either a 5, 15 or 30min recovery period. The exercise bout was of moderate-intensity (40-59% of HRR). Mood profile was assessed from the POMS survey, considering subscales of depression, anger and hostility.

RESULTS

For all three mood profile parameters, there was no evidence of a group x time interaction effect. However, the main effect for time was statistically significant for each mood parameter. These significant results demonstrate that, generally, exercise had a favorable effect on each of the mood profile, regardless of exercise duration and recovery period. In addition to the significant main effects for time, we also observed a significant main effect for group for the mood parameter hostility. With the exception of the group 13 (60min of exercise with 5min recovery) and the 3 groups that employed a 10-min bout of exercise (groups 1-3), all other experimental groups had a lower (better) hostility score after the exercise visit.

CONCLUSIONS

Generally, exercise had a favorable effect on various mood profiles, regardless of exercise duration (between 10 and 60min) and recovery period (between 5 and 30min).

Dose-Response Effects of Exercise Duration and Recovery on Cognitive Functioning

We examined the effects of different acute exercise durations and recovery periods on cognitive function in a counterbalanced, cross-over randomized controlled experiment. We placed 352 participants, aged 18 to 35 years into one of 16 experimental groups. Each participant visited the laboratory twice, separated by a 1-week washout period. Either Visit 1 or 2 consisted of an acute bout of moderate-intensity treadmill exercise (10, 20, 30, 45, or 60 minutes) followed by a period of rest (5, 15, or 30 minutes) before taking a set of five cognitive tests; the other visit consisted only of completing the cognitive tests (no exercise). Cognitive tests sampled multiple cognitive parameters, including reasoning, concentration, memory, attention, and planning. We found that a short recovery period (i.e., 5 minutes) may have a less favorable effect on planning ability but may be beneficial for memory. In addition, for various exercise durations and recovery periods, a Group × Time × Resting (nonexercise) A cognitive interaction effect was observed such that for both memory and inhibitory cognitive ability, acute exercise (vs. no exercise) had an enhancement effect for those with lower resting cognitive functioning. The length of the acute exercise recovery period and resting cognitive ability most influenced the association between exercise and cognitive function.

Assessing the accuracy of algorithm-derived cardiorespiratory fitness in surgical patients: a prospective cohort study

PURPOSE

To determine if a non-exercise algorithm-derived assessment of cardiorespiratory fitness (CRF_A) accurately predicted estimated values obtained using a six-minute walk test (CRF_6MWD) and the Duke Activity Status Index (CRF_DASI).

METHODS

Following research ethics board approval, an observational cohort study was conducted in selected, consenting patients undergoing elective surgery. Participants completed questionnaires assessing their self-reported exercise capacity. Their height, weight, waist circumference, and vital signs were measured. A six-minute walk test was performed twice with a 45-min rest interval between tests. The correlation between CRF_A and both CRF_6MWD and CRF_DASI was determined.

RESULTS

Two hundred forty-two participants were included. Mean age was 62 (range 45-88 yr); 150 (62%) were male, 87 (36%) self-reported walking or jogging > 16 km per week, and 49 (20%) were current smokers. The CRF_A and CRF_6MWD were highly correlated (Pearson r = 0.878; P < 0.001). CRF_A and CRF_DASI were less strongly correlated (Pearson r = 0.252; P < 0.001). Among patients capable of walking > 427 m in the six-minute walk test, CRF_A, CRF_6MWD, and CRF_DASI were equivalent.

CONCLUSION

A non-exercise algorithm can estimate cardiorespiratory fitness in patients presenting for elective surgery. The variables required to compute CRF_A can be obtained in a clinic setting without the need to engage in formal exercise testing. Further evaluation of CRF_A as a predictor of long-term outcome in patients is warranted.

Hostility and social support explain physical activity beyond negative affect among young men, but not women, in college

We examined social support as a moderator of cynical hostility in relation to physical activity and body mass index among college students (n = 859; M = 18.71 years (SD = 1.22); 60% women, 84% White). After controlling for negative affect in hierarchical linear regression models, greater hostility was associated with lesser physical activity among those with low social support, as expected. Greater hostility was also associated with greater physical activity among those high in social support, ps < .05. Effects were observed for men only. Hostility and social support were unrelated to body mass index, ps > .05. Young men with a hostile disposition and low social support may be at risk for a sedentary lifestyle for reasons other than negative affect.

Physical activity does not mitigate G-protein-related genetic risk for obesity in individuals of African descent

The G-protein beta3 subunit 825 TT genotype has been associated with obesity and hypertension. We examined the interaction between the G-protein TT genotype, physical activity and body mass index (BMI) in a cross-sectional study of African immigrants and African Americans. The genotype frequencies were 6.3% CC, 37.7% CT, and 56% TT. After adjusting for potential confounders, BMI was found to be significantly higher in the sedentary than in the physically active participants (p=0.045). There was no statistically significant effect for genotype (p=0.215) or the interaction between genotype and the level of physical activity (p=0.219). However, the individuals with the CC or CT genotype who were physically active had substantially lower BMIs (M+/-SE) (i.e., 25.74+/-2.02) than any of the other groups: sedentary CC + CT (30.58+/-1.03), sedentary TT (30.65+/-1.00) or active TT (29.43+/-1.65). Because of the low statistical power of this study, further research is needed to confirm these findings and to explore potential gene-environment/lifestyle interactions.

Classification of cardiorespiratory fitness without exercise testing

PURPOSE

We examined the ability of a nonexercise based VO2max, prediction model to classify cardiorespiratory fitness (CRF) in a population of men and women aged 19-79 yr of age (N = 799).

METHODS

A VO2max (mL.kg(-1).min(-1)) prediction model was developed in the study group using multiple linear regression from the independent variables age, age2, gender, physical activity status, height, and body mass. The classification accuracy of this model was examined by cross-tabulating age and gender specific quintiles of measured and predicted CRF.

RESULTS

Overall classification accuracy of the model was modest (36%); however, 83% of all subjects were either classified correctly or within one quintile of measured CRF. Extreme misclassification (e.g., misclassifying a low fit individual as high fit) was only rarely observed (0.13%).

CONCLUSIONS

The present results support the concept that CRF prediction models can be used to reasonably characterize the fitness level of a cohort using data that can be obtained from a questionnaire. Accordingly, predicted CRF values may be useful as an exposure variable in large epidemiologic studies in which exercise testing is not feasible.