Caffeine has been described as a sports performance-enhancing substance. However, it is unclear whether it can increase the level of physical activity (PA) in nonathletic individuals. This study investigates the relationship between daily caffeine consumption and (a) daily PA/fitness or (b) intervention-induced changes in PA in women and men. On the basis of responses to a dietary habit questionnaire, which included items on caffeinated beverages, 1,032 Japanese adults, were categorized into lower or higher caffeine consumption groups (relative to the median caffeine consumption). In each group, daily step count; sedentary time; and light, moderate, and vigorous PA outcomes were objectively measured. Physical fitness, including peak oxygen consumption, was also evaluated. The relationship between daily caffeine consumption and the change in the levels of PA was investigated in a subgroup of 202 subjects who participated in a 1-year PA counseling intervention. Women in the higher caffeine consumption group presented higher moderate-to-vigorous PA and step count compared with their counterparts in the lower consumption group (4.0 ± 2.1 vs. 3.3 ± 2.1 MET-hr/day, p < .001; 10,335 ± 3,499 vs. 9,375 ± 3,527 steps/day, p < .001). A significant positive correlation was noted between caffeine consumption and peak oxygen consumption among women (r = .15, p < .001). No caffeine-related effects were noted in men. The lower and higher caffeine consumption groups showed no significant differences in their levels of PA at the end of the 1-year intervention. Therefore, caffeine consumption appears to be associated with higher levels of PA in Japanese women. Further studies are needed to clarify this association.
Julien Tripette, Haruka Murakami, Hidemi Hara, Ryoko Kawakami, Yuko Gando, Harumi Ohno, Nobuyuki Miyatake and Motohiko Miyachi
Chiaki Tanaka, Shigeho Tanaka, Shigeru Inoue, Motohiko Miyachi, Koya Suzuki, Takafumi Abe and John J. Reilly
Chiaki Tanaka, Shigeho Tanaka, Shigeru Inoue, Motohiko Miyachi, Koya Suzuki and John J. Reilly
The Report Card on Physical Activity for Children and Youth aims to consolidate existing evidence, encourage greater evidence-informed physical activity, and improve surveillance of physical activity.
The Japan report card followed the methodology of the Canadian and Scottish report cards, but was adapted to reflect the Japanese context. Nationally representative data were used to score each of the respective indicators.
The 2016 Japan Report Card on Physical Activity for Children and Youth consists of Health Behaviors and Outcomes (7 indicators), and Influences on Health Behaviors (4 indicators). Three Health Behaviors and Outcomes received C grades (Participation in Sport; Sedentary Behavior; Recreational Screen Time; Physical Fitness), while 2 indicators could not be graded (Overall Physical Activity, and Active Play). The indicators Active Transportation (B) and Weight Status were favorable (A). In the Influences domain, Family Influence and Community and the Built Environment were graded as D, while School and Government Strategies and Investments were favorable (B).
The Japan report card illustrated some favorable health behaviors, health outcomes, and influences. There is a need for more evidence especially on overall physical activity levels, active play, and community and the built environment.
Yuko Gando, Haruka Murakami, Ryoko Kawakami, Noriko Tanaka, Kiyoshi Sanada, Izumi Tabata, Mitsuru Higuchi and Motohiko Miyachi
It is unclear whether light physical activity is beneficially associated with insulin resistance, similar to moderate and/or vigorous physical activity. This cross-sectional study was performed to determine the relationship between the amount of light physical activity, as determined with a triaxial accelerometer, and insulin resistance.
A total of 807 healthy men and women participated in this study. Physical activity was measured using a triaxial accelerometer worn for 28 days and summarized as light intensity (1.1–2.9 METs) or moderate to vigorous intensity (≥ 3.0 METs). Insulin resistance was evaluated by HOMA_R (FPG [mg/dL] × IRI [μU/mL]/405).
The daily time spent in light physical activity was inversely associated with HOMA_R (r = –0.173, P < 0.05). After adjustment for confounders, the association between light physical activity and HOMA_R remained statistically significant (β = –0.119, P < .05). Light physical activity remained significantly associated with HOMA_R following further adjustment for moderate to vigorous intensity activity (β = –0.125, P < .05). Similar results were observed when light physical activity was modeled as quartiles, especially in elderly women.
These cross-sectional data suggest that light-intensity physical activity is beneficially associated with insulin resistance in elderly Japanese women.
Yuya Watanabe, Michiya Tanimoto, Akane Ohgane, Kiyoshi Sanada, Motohiko Miyachi and Naokata Ishii
The authors investigated the effects of low-intensity resistance training on muscle size and strength in older men and women. Thirty-five participants (age 59–76 yr) were randomly assigned to 2 groups and performed low-intensity (50% of 1-repetition maximum) knee-extension and -flexion exercises with either slow movement and tonic force generation (LST; 3-s eccentric, 3-s concentric, and 1-s isometric actions with no rest between repetitions) or normal speed (LN; 1-s concentric and 1-s eccentric actions with 1-s rests between repetitions) twice a week for 12 wk (2-wk preparation and 10-wk intervention). The LST significantly increased thigh-muscle thickness, as well as isometric knee-extension and -flexion strength. The LN significantly improved strength, but its hypertrophic effect was limited. These results indicate that even for older individuals, the LST can be an effective method for gaining muscle mass and strength.
Yuko Hashimoto, Ko Matsudaira, Susumu S. Sawada, Yuko Gando, Ryoko Kawakami, Chihiro Kinugawa, Takashi Okamoto, Koji Tsukamoto, Motohiko Miyachi, Hisashi Naito and Steven N. Blair
Background: There are several studies on the relationship between low back pain and physical activity. However, the results of these studies vary, and the relationship between them remains unclear. Therefore, we conducted a cross-sectional study to evaluate the association between objectively measured physical activity and low back pain in Japanese men. Methods: The study included 4022 Japanese men [average age: 47 (10) y]. Daily amount of moderate to vigorous physical activity and step counts were measured using an accelerometer. Low back pain, drinking and smoking, and lifestyle-related diseases were surveyed using a self-administered questionnaire. A logistic regression model was used to evaluate the relationship between physical activity and step counts with persistent low back pain after adjusting for confounders. Results: Persistent low back pain was reported in 428 participants. The multivariable-adjusted odds ratios of presenting persistent low back pain across quartiles of amount of moderate to vigorous physical activity were 1.00 (reference); 0.93 (95% confidence interval, 0.70–1.22); 0.97 (95% confidence interval, 0.74–1.28); and 0.67 (95% confidence interval, 0.50–0.90); P for linearity = .012. Conclusion: We found a significant inverse relationship between objectively measured physical activity and persistent low back pain.