Judith A. Juvancic-Heltzel

The Effect of Variety on Physical Activity: A Cross-Sectional Study

Abstract Juvancic-Heltzel, JA, Glickman, EL, and Barkley, JE. The effect of variety on physical activity: A cross-sectional study. J Strength Cond Res 27(1): 244–251, 2013—It has been repeatedly demonstrated that increasing the variety of available food and purchasing options reliably increases eating and consumer spending behavior, respectively. However, the potential probehavioral effect of increasing the variety of exercise equipment options on the amount of exercise individuals perform is very limited. The purpose of this investigation was to compare the amount, enjoyment (liking), and effort perception of resistance training exercise vs. sedentary alternatives during a high-variety (HV) resistance-exercise equipment condition (10 choices) vs. a low-variety (LV) equipment condition (2 choices). During each condition (HV) and (LV), children (8–12 years), young adults (18–26 years), and older adults (≥60 years) had free-choice access to both resistance-exercise equipment and sedentary activities for a total of 20 minutes. The amount of time allocated to resistance exercise, the total number of repetitions performed, and session liking were measured during each condition. The participants significantly (p ⩽ 0.05 for all) increased: repetitions performed (126.4 ± 71.7 vs. 88.0 ± 48.8), the amount of time allocated for exercise (14.3 ± 6.3 vs. 12.1 ± 6.5 minutes) and liking (8.1 ± 1.5 vs. 7.1 ± 2.1 cm) during the HV condition relative to the LV condition. The rating of perceived exertion was not significantly (p = 0.13) different from HV (4.2 ± 2.4) to LV (3.8 ± 2.3). Increasing the variety of exercise equipment available to children, young and older adults increased their exercise participation and enjoyment of that exercise without altering their perceived exertion. The practical application from this research is that increasing the variety of exercise equipment available to ones clients may increase their exercise adherence.

Serum brain-derived neurotrophic factor is associated with reduced appetite in healthy older adults.

Objective: Loss of appetite and body mass are common in older adults and are associated with negative consequences. Research indicates that these processes likely involve increases in serum brain-derived neurotrophic factor (BDNF). Animal and human models demonstrate that BDNF may serve a regulatory function in food intake, but no study has addressed the possibility that BDNF may be involved in appetite reduction and loss of body mass in older adults.Design and Participants: 34 older adults without significant neurological or psychiatric history underwent fasting blood draw and measurement of body composition. Appetite and eating behavior were assessed by questionnaire and related to serum BDNF levels.Results: Partial correlations showed serum BDNF levels were inversely related to appetite (r = −.38, p = .02). No significant correlations emerged between serum BDNF and age, diet, or body composition.Conclusions: The current study extends past work and shows that BDNF is associated with appetite in healthy older adults. Further work is needed to clarify mechanisms for these findings, particularly prospective studies.

Fifty-Three Hours of Total Sleep Deprivation Has No Effect on Rewarming From Cold Air Exposure

OBJECTIVE Sleep deprivation and cold air exposure are both experienced in occupational and military settings but the combined effects of these 2 stressors is unknown. The purpose of this study was to determine the effects of 53 hours of total sleep deprivation on thermoregulation during the rewarming phase (25°C air) after acute cold air exposure (10°C air). METHODS Eight young men underwent 2 trials in which they either received 7 hours of sleep at night or were totally sleep deprived. On 3 consecutive mornings, the subjects underwent 2 hours of cold air exposure followed by 2 hours of rewarming. Rectal temperature, mean skin temperature, oxygen consumption, and thermal sensation were measured. RESULTS Rewarming from acute cold air exposure caused a decline in rectal temperature (~0.5°C) each day but this was not different between subjects who were totally sleep deprived and subjects who received 7 hours of sleep at night. During this same period, mean skin temperature increased (from ~22°C to 27°C), oxygen consumption decreased (from ~7 to 4 mL·kg(-1)·min(-1)), and the participants felt warmer. CONCLUSIONS Under the conditions of the present study, sleep-deprived persons are not at a greater risk for a decline in rectal temperature (ie, a hypothermic afterdrop) during rewarming from cold air.