Physical fitness, achieved through regular exercise and/or spontaneous physical activity, confers resilience by inducing positive psychological and physiological benefits, blunting stress reactivity, protecting against potentially adverse behavioural and metabolic consequences of stressful events and preventing many chronic diseases. In this review, we discuss the biological mechanisms underlying the beneficial effects of physical fitness on mental and physical health. Physical fitness appears to buffer against stress-related disease owing to its blunting/optimizing effects on hormonal stress responsive systems, such as the hypothalamic–pituitary–adrenal axis and the sympathetic nervous system. This blunting appears to contribute to reduced emotional, physiological and metabolic reactivity as well as increased positive mood and well-being. Another mechanism whereby regular exercise and/or physical fitness may confer resilience is through minimizing excessive inflammation. Chronic psychological stress, physical inactivity and abdominal adiposity have been associated with persistent, systemic, low-grade inflammation and exert adverse effects on mental and physical health. The anti-inflammatory effects of regular exercise/activity can promote behavioural and metabolic resilience, and protect against various chronic diseases associated with systemic inflammation. Moreover, exercise may benefit the brain by enhancing growth factor expression and neural plasticity, thereby contributing to improved mood and cognition. In summary, the mechanisms whereby physical fitness promotes increased resilience and well-being and positive psychological and physical health are diverse and complex.

Injury in a large military cohort. Methods A cohort of 874 Marine officer candidates were recruited, consented, completed demographic questionnaires, and had FMS performed during medical in-processing. Candidates were enrolled in either long-cycle (LC: 68 d; n = 427) or short-cycle (SC: 38 d; n = 447) training and followed up for injuries occurring in training. Results The mean FMS score (score range = 0–21) among all candidates was 16.6 ± 1.7; approximately 10% of candidates had FMS scores ≤14. A score of ≤14 on the FMS predicted any injury with a sensitivity of 0.45 and a specificity of 0.71 and serious injury with a sensitivity of 0.12 and a specificity of 0.94. Both LC and SC cohorts demonstrated higher injury risk among candidates who had scores ≤14 compared with those with scores >14 (LC: risk ratio (RR) = 1.65, 95% confidence interval = 1.05–2.59, P = 0.03; SC: RR = 1.91, 95% confidence interval = 1.21–3.01, P < 0.01). Overall, 79.8% of persons with scores ≤14 were in the group with fitness scores <280 (/300), whereas only 6.6% of candidates in the group with fitness scores ≥280 had scores ≤14. Conclusions This was the first large-scale study performed in an active-duty military cohort to examine the utility of FMS during medical in-processing. Further work is warranted to evaluate FMS and the potential for injury prediction and prevention....

= 447) or 10 wk (n = 427) of Marine Corps officer candidate training was recruited. They completed an exercise history questionnaire, underwent an FMS during medical in-processing, and completed the standardized PFT (pull-ups, abdominal crunch, and 3-mile run) within 1 wk of training. Injury data were gathered throughout training from medical records and classified into overuse, traumatic, and any injury. Results Three-mile run time (RT) was the only PFT component predictive of injury: candidates with RT ≥20.5 min were 1.7 times (95% confidence interval = 1.29–2.31, P < 0.001) more likely to experience an injury compared with those with RT <20.5 min. Prior injury, frequency of general exercise and sport participation, and length of running history were predictive of any, overuse, and traumatic injuries, respectively. Combining slow RT and low FMS scores (≤14) increased the predictive value across all injury classifications: candidates scoring poorly on both tests were 4.2 times more likely to experience an injury. The pull-up to exhaustion test was related to four of the seven FMS tests and the only PFT test positively related to total FMS score, although correlations were generally low (r ≤ 0.11). Conclusion Slow RT was associated with increased injury risk, and combining poor RT and low FMS scores significantly increased the injury predictive value. Additional research is warranted to further clarify what combination of PFT and FMS tests are most suitable for predicting injuries....

To investigate the influence of various biological, socioeconomic, and behavioral factors on premenstrual syndrome (PMS). Random-digit dialing technique. Of 7900 calls from all area codes, exchanges, and 2 digits known to be open in Virginia, with a pair of random digits, 1700 women were eligible for telephone interviews. A total of 874 women completed interviews, for a response rate of 67%. State of Virginia. All women between the ages of 18 and 44 years and living in Virginia between August 1 and September 15, 1994, were eligible. Scores on Menstrual Distress Questionnaire, biological variables, lifestyle behaviors, socioeconomic status, and menstrual and reproductive history. Of the 874 women, 8.3% (95% confidence interval, 6.4%-10.2%) experienced PMS. Adjusted prevalence odds ratios for perceived stress and alcohol intake were 3.7 and 2.5, respectively, in women with PMS. Women with PMS were 2.9 times more likely to be physically active than women without PMS. Younger women, black women, and women with longer menses were more likely to have PMS. Scores on the stress scale and alcohol intake support the concept that PMS is stress related; intervention strategies to cope with stress may be effective. Further study will be required to determine the influence of race on PMS and whether women with PMS exercise more regularly than women without PMS because they believe exercise is effective in attenuating their symptoms.

Previous studies in animals indicate that reproductive steroids are potent modulators of the hypothalamic-pituitary-adrenal (HPA) axis, a physiologic system that is typically dysregulated in affective disorders, such as major depression. Determination of the role of reproductive steroids in HPA axis regulation in humans is of importance when attempting to understand the pathophysiology of premenstrual syndrome (PMS), a disorder characterized by affective symptoms during the luteal phase of the menstrual cycle. We performed two studies using treadmill exercise stress testing to determine the effect of menstrual cycle phase and diagnosis on the HPA axis in women with PMS and controls and the role of gonadal steroids in HPA axis modulation in control women. The results of these studies indicate that women with PMS fail to show the normal increased HPA axis response to exercise during the luteal phase and that progesterone, not estradiol, produces increased HPA axis response to treadmill stress testing in control women. These data demonstrate that women with PMS, when symptomatic, appear to have an abnormal response to progesterone and, furthermore, do not display the HPA axis abnormalities characteristic of major depression.