Scanning Sports Medicine
ASSOCIATIONS BETWEEN PHYSICAL ACTIVITY AND PHYSICAL AND MENTAL HEALTH - A HUNT 3 STUDY
The authors of this study in the July 2011 issue of Medicine & Science in Sports & Exercise® investigated the relationship of frequency, duration, and intensity of physical activity as it relates to health-related quality of life (HRQoL) in both younger (<65 yr) and older adults (>65 yr) (1). The study used a population-based cross-sectional sample of 4,500 participants where subjects were between the ages of 19 and 91 yr old with a mean age of 53 yr. HRQoL was measured using the SF-8 Health Survey. Frequency and duration of physical activity were assessed using items validated in previous HUNT studies, whereas intensity was measured with the Borg RPE scale. The associations between physical activity and physical and mental health were estimated using general linear modeling.
The findings of the study demonstrated that age-adjusted association between physical activity and HRQoL was stronger for physical rather than mental health in both genders and age groups. The largest differences existed between the nonexercise and the exercise groups at any level for frequency, duration, and intensity of physical activity. There were no substantial gender differences in association between physical activity and HRQoL, but the association was stronger in older versus younger subjects.
Bottom line: This study lends further support to the fact that exercise at any level is associated with better physical and mental health in both genders and is especially beneficial in older populations.
Exercise Dosing to Retain Resistance Training Adaptations in Younger and Older Adults
In the July 2011 issue of Medicine & Science in Sports & Exercise®, authors tested the efficacy of two maintenance prescriptions on muscle mass, myofiber size and type distribution, and strength in old (60 to 75 yr) versus young (20 to 35 yr) subjects (2). These measures were looked at in an attempt to better define dosing requirements required to maintain strength gains when resistance training (RT) is used as a means to counteract sarcopenia. The hypothesis was that the minimum dose required to maintain RT-induced adaptations would be greater in the older subjects.
The study consisted of 70 adults who participated in a two-phase exercise trial. Phase I consisted of RT 3 d·wk−1 for 16 wk; this was followed by a 32-wk phase II period where subjects were randomly assigned to either detraining or one of two maintenance prescriptions. The maintenance prescriptions were either one-third or one-ninth of the RT dose from phase I. Results of phase I demonstrated the expected gains in strength, myofiber size, and muscle mass along with the typical IIx-to-IIa shift in myofiber type distribution. Both maintenance prescriptions in phase II were able to preserve the muscle hypertrophy gains in the young subjects but not in the old subjects. Both age groups demonstrated that detraining reversed the phase I IIx-to-IIa myofiber changes, whereas a dose-response was seen during maintenance training with one-third of the dose better maintaining the shift. The strength gained during phase I was largely maintained throughout detraining. The authors concluded that older adults require a higher dose of weekly loading than younger adults to maintain myofiber hypertrophy attained during an RT program but that gains in specific strength among older adults were well preserved and remained at or above the levels of untrained young adults.
Bottom line: This study was able to demonstrate that a once-per-week RT exercise dose was generally sufficient to maintain positive neuromuscular adaptations in both younger and older adults, although age-specific differences were observed in the required minimum dose for maintenance of muscle size.
1. Bertheussen GF, Romundstad PR, Landmark T, et al
. Associations between physical activity and physical and mental health - a HUNT 3 study. Med. Sci. Sports Exerc
. 2011; 43:1220-28.
2. Bickel SC, Cross JM, Bamman MM. Exercise dosing to retain resistance training adaptations in young and older adults. Med. Sci. Sports Exerc
. 2011; 43:1177-87.