If your goal is to increase your muscular strength this year, your first step should be to turn off the television. A recent Finnish study published in the November 2009 issue of Medicine & Science in Sports & Exercise found that young adults (mean age 19.1 years) who watched more than 2 hours of television per day had lower levels of muscular fitness, despite regular participation in moderate-vigorous physical activity, when compared to individuals who viewed less than 2 hours of TV per day. This effect was more pronounced in females who watched high amounts of television than in males, although both genders had lower muscular fitness levels associated with higher levels of television viewing.

The muscular fitness levels of 874 subjects (381 males and 493 females) were assessed from trunk flexion, extension, and rotation strength tests and a jumping height test (countermovement jump) which measured the speed-strength of the leg extensor muscles. Subjects self-reported hours of physical activity and television viewing. Males performed better on all strength tests than did the females and they were more physically active. However, there was no significant difference between genders in the amount of television viewed.

Males who watched high amounts of television had lower scores on the trunk extension and flexion tests compared to their male counterparts who viewed fewer hours. Those females who watched more than 2 hours of television per day scored significantly less on all tests compared to the women subjects who watched less than 2 hours of television per day. All subjects who reported participation in high levels of physical activity exhibited better scores on the muscular fitness tests.

Prior research has indicated that prolonged periods of sitting are associated with a greater incidence of mortality from cardiovascular disease and all causes, except cancer - irrespective of activity level (see "Don't Take it Sitting Down," May 14, 2009). Investigators from the recent Finnish study state that their research is the first to report findings of an association between high amounts of TV viewing and lower muscular fitness levels in young adults. The researchers also highlight that low levels of physical activity and an increased volume of television viewing are independently associated with poorer muscular fitness scores.

Investigators were stunned that about half of the Finnish subjects studied viewed at least 2 hours of television per day, accumulating almost a total of 15 hours of TV watching in a week's time. For Americans, who on average watch more than 4 hours of television per day according to Nielsen ratings, the impact on muscular fitness could be greater. The researchers note that this time could be spent participating in activities that promote health and fitness.

A limitation of this study is that the physical activity levels were self-reported and mode of exercise was not recorded. The poorer muscular fitness levels observed in the study, despite regular physical activity, could be a reflection of a lack of participation in strength training exercises. Investigators encourage young adults to follow recommendations to include strength training activities of the major muscle groups of the body at least 2 times per week. And, that television viewing should be limited to less than 2 hours per day.

Note: Before beginning an exercise program or increasing the intensity level of a current routine, a physician's approval should be obtained, especially for older adults and those at risk for or who currently have chronic health conditions.

Resource:

Medicine & Science in Sports & Exercise, November 2009, Volume 41, Number 11, pp. 1997-2001, "Muscular Fitness in Relation to Physical Activity and Television Viewing among Young Adults," Paalanne, N.K. et al.