Bone marrow metabolism is affected by body weight and response to exercise training varies according to anatomical location.

AIM: High body weight is a protective factor against osteoporosis, but obesity also suppresses bone metabolism and whole-body insulin sensitivity. However, the impact of body weight and regular training on bone marrow (BM) glucose metabolism is unclear. We studied the effects of regular exercise training on bone and BM metabolism in monozygotic twin pairs discordant for body weight. METHODS: We recruited 12 monozygotic twin pairs (mean ± SD age 40.4 ± 4.5 years; body mass index 32.9 ± 7.6, mean difference between co-twins 7.6 kg/m2 ; eight female pairs). Ten pairs completed the 6-month long training intervention. We measured lumbar vertebral and femoral BM insulin-stimulated glucose uptake (GU) using 18 F-FDG positron emission tomography, lumbar spine bone mineral density and bone turnover markers. RESULTS: At baseline, heavier co-twins had higher lumbar vertebral BM GU (p < .001) and lower bone turnover markers (all p < .01) compared with leaner co-twins but there was no significant difference in femoral BM GU, or bone mineral density. Training improved whole-body insulin sensitivity, aerobic capacity (both p < .05) and femoral BM GU (p = .008). The training response in lumbar vertebral BM GU was different between the groups (time × group, p = .02), as GU tended to decrease in heavier co-twins (p = .06) while there was no change in leaner co-twins. CONCLUSIONS: In this study, regular exercise training increases femoral BM GU regardless of weight and genetics. Interestingly, lumbar vertebral BM GU is higher in participants with higher body weight, and training counteracts this effect in heavier co-twins even without reduction in weight. These data suggest that BM metabolism is altered by physical activity.

Endurance training volume cannot entirely substitute for the lack of intensity.

PURPOSE: Very low intensity endurance training (LIT) does not seem to improve maximal oxygen uptake. The purpose of the present study was to investigate if very high volume of LIT could compensate the lack of intensity and is LIT affecting differently low and high intensity performances. METHODS: Recreationally active untrained participants (n = 35; 21 females) cycled either LIT (mean training time 6.7 ± 0.7 h / week at 63% of maximal heart rate, n = 16) or high intensity training (HIT) (1.6 ± 0.2 h /week, n = 19) for 10 weeks. Two categories of variables were measured: Low (first lactate threshold, fat oxidation at low intensity exercise, post-exercise recovery) and high (aerobic capacity, second lactate threshold, sprinting power, maximal stroke volume) intensity performance. RESULTS: Only LIT enhanced pooled low intensity performance (LIT: p = 0.01, ES = 0.49, HIT: p = 0.20, ES = 0.20) and HIT pooled high intensity performance (LIT: p = 0.34, ES = 0.05, HIT: p = 0.007, ES = 0.48). CONCLUSIONS: Overall, very low endurance training intensity cannot fully be compensated by high training volume in adaptations to high intensity performance, but it nevertheless improved low intensity performance. Therefore, the intensity threshold for improving low intensity performance is lower than that for improving high intensity performance. Consequently, evaluating the effectiveness of LIT on endurance performance cannot be solely determined by high intensity performance tests.

How to Equalize High- and Low-Intensity Endurance Exercise Dose.

PURPOSE: Without appropriate standardization of exercise doses, comparing high- (HI) and low-intensity (LI) training outcomes might become a matter of speculation. In athletic preparation, proper quantification ensures an optimized stress-to-recovery ratio. This review aims to compare HI and LI doses by estimating theoretically the conversion ratio, 1:x, between HI and LI: How many minutes, x, of LI are equivalent to 1 minute of HI using various quantification methods? A scrutinized analysis on how the dose increases in relation to duration and intensity was also made. ANALYSIS: An estimation was conducted across 4 categories encompassing 10 different approaches: (1) "arbitrary" methods, (2) physiological and perceptual measurements during exercise, (3) postexercise measurements, and comparison to (4a) acute and (4b) chronic intensity-related maximum dose. The first 2 categories provide the most conservative estimation for the HI:LI ratio (1:1.5-1:10), and the third, slightly higher (1:4-1:11). The category (4a) provides the highest estimation (1:52+) and (4b) suggests 1:10 to 1:20. The exercise dose in the majority of the approaches increase linearly in relation to duration and exponentially in relation to intensity. CONCLUSIONS: As dose estimations provide divergent evaluations of the HI:LI ratio, the choice of metric will have a large impact on the research designs, results, and interpretations. Therefore, researchers should familiarize themselves with the foundations and weaknesses of their metrics and justify their choice. Last, the linear relationship between duration and exercise dose is in many cases assumed rather than thoroughly tested, and its use should be subjected to closer scrutiny.

Contraction of Respiratory Viral Infection During air Travel: An Under-Recognized Health Risk for Athletes.

Air travel has an important role in the spread of viral acute respiratory infections (ARIs). Aircraft offer an ideal setting for the transmission of ARI because of a closed environment, crowded conditions, and close-contact setting. Numerous studies have shown that influenza and COVID-19 spread readily in an aircraft with one virus-positive symptomatic or asymptomatic index case. The numbers of secondary cases differ markedly in different studies most probably because of the wide variation of the infectiousness of the infector as well as the susceptibility of the infectees. The primary risk factor is sitting within two rows of an infectious passenger. Elite athletes travel frequently and are thus prone to contracting an ARI during travel. It is anecdotally known in the sport and exercise medicine community that athletes often contract ARI during air travel. The degree to which athletes are infected in an aircraft by respiratory viruses is unclear. Two recent studies suggest that 8% of Team Finland members traveling to major winter sports events contracted the common cold most probably during air travel. Further prospective clinical studies with viral diagnostics are needed to understand the transmission dynamics and to develop effective and socially acceptable preventive measures during air travel.

Perceived coaches' health promotion activity, maintenance of participation in sports, and lifestyle habits among emerging adults: a four-year follow-up study.

OBJECTIVES: This study focused on how adolescents' perceptions of coaches' health promotion activity predict maintained participation and dropout in organized sports in emerging adulthood. In addition, differences in lifestyle habits between maintainers, dropouts, and nonparticipants in organized sports were explored. MATERIALS AND METHODS: Overall, 616 adolescents reported organized sports participation in the Finnish Health Promoting Sports Club (FHPSC) study at ages 15 and 19. Of these, 323 reported coach's health promotion activity on health topics at the age of 15. An index of a coach's general health promotion activity was formed. At age 19, all study participants reported their lifestyle habits. RESULTS: Among males, those who had perceived coaches' general health promotion activity as frequent were more likely to be maintainers than dropouts (48.6% vs. 20.0%) (p = .002). Among females, there was no significant difference (32.0% vs. 28.4%). Logistic regression analysis adjusted for gender showed that perceiving coach's general health promotion activity as frequent increased the odds of being a maintainer rather than a dropout. Moreover, maintainers had higher odds of having healthy lifestyle habits when compared to nonparticipants (related to physical activity; sleep; fruit and vegetable consumption; and cigarette use) or dropouts (related to physical activity; and cigarette use). In addition, dropouts had higher odds of having healthy lifestyle habits than nonparticipants (related to sleep; and cigarette use). CONCLUSIONS: Perceiving coaches' health promotion activity as frequent was related to maintained participation in organized sports among males. Maintainers were more likely to have more healthy lifestyle habits than nonparticipants and dropouts. There is a need to invest in coaches' health promotion activity when it is infrequent. A more detailed understanding is needed of coaches' health promotion activity that supports both maintained participation in sports, especially among females, and healthy lifestyle habits in emerging adulthood.

There is a need to invest in coaches' health promotion activity when it is infrequent in order to support adolescents' continued participation in organized sports and healthy lifestyle habits in emerging adulthood.

Association of Ideal Cardiovascular Health in Youth with Cancer Risk in Adulthood: A Cardiovascular Risk in Young Finns Study.

BACKGROUND: Lifestyle factors may affect cancer risk. This study aimed to identify whether the American Heart Association ideal cardiovascular health (ICH) score and its individual variables in youth are associated with subsequent cancer incidence. METHODS: This study comprised participants of the Cardiovascular Risk in Young Finns Study free of cancer at the analysis baseline in 1986 (n = 1,873). The baseline age was 12 to 24 years, and the follow-up occurred between 1986 and 2018. RESULTS: Among 1,873 participants (mean age 17.3 ± 4.1 years; 53.4% females at baseline), 72 incident cancer cases occurred during the follow-up (mean follow-up time 31.4 ± 3.4 years). Baseline ICH score was not associated with future cancer risk (HR, 0.96; 95% confidence interval, 0.78-1.12 per 1-point increment). Of individual ICH score variables, ideal physical activity (PA) was inversely associated with cancer incidence [age- and sex-adjusted HR, 0.45 (0.23-0.88) per 1-category change (nonideal/ideal)] and remained significant in the multivariable-adjusted model, including body mass index, smoking, diet, and socioeconomic status. A continuous PA index at ages 9 to 24 years and moderate-to-vigorous PA in youth were also related to decreased cancer incidence (P < 0.05). Body mass index, smoking, diet, total cholesterol, glucose, and blood pressure were not related to cancer risk. Of the dietary components, meat consumption was associated with cancer incidence (P = 0.023). CONCLUSIONS: These findings indicate that higher PA levels in youth are associated with a reduced subsequent cancer incidence, whereas the American Heart Association's ICH score in youth does not. IMPACT: This finding supports efforts to promote a healthy lifestyle and encourages PA during childhood, yielding a subsequent healthier life.