The purpose of this Position Stand is to provide guidance to professionals who counsel and prescribe individualized exercise to apparently healthy adults of all ages. These recommendations also may apply to adults with certain chronic diseases or disabilities, when appropriately evaluated and advised by a health professional. This document supersedes the 1998 American College of Sports Medicine (ACSM) Position Stand, "The Recommended Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory and Muscular Fitness, and Flexibility in Healthy Adults." The scientific evidence demonstrating the beneficial effects of exercise is indisputable, and the benefits of exercise far outweigh the risks in most adults. A program of regular exercise that includes cardiorespiratory, resistance, flexibility, and neuromotor exercise training beyond activities of daily living to improve and maintain physical fitness and health is essential for most adults. The ACSM recommends that most adults engage in moderate-intensity cardiorespiratory exercise training for ≥30 min·d on ≥5 d·wk for a total of ≥150 min·wk, vigorous-intensity cardiorespiratory exercise training for ≥20 min·d on ≥3 d·wk (≥75 min·wk), or a combination of moderate- and vigorous-intensity exercise to achieve a total energy expenditure of ≥500-1000 MET·min·wk. On 2-3 d·wk, adults should also perform resistance exercises for each of the major muscle groups, and neuromotor exercise involving balance, agility, and coordination. Crucial to maintaining joint range of movement, completing a series of flexibility exercises for each the major muscle-tendon groups (a total of 60 s per exercise) on ≥2 d·wk is recommended. The exercise program should be modified according to an individual's habitual physical activity, physical function, health status, exercise responses, and stated goals. Adults who are unable or unwilling to meet the exercise targets outlined here still can benefit from engaging in amounts of exercise less than recommended. In addition to exercising regularly, there are health benefits in concurrently reducing total time engaged in sedentary pursuits and also by interspersing frequent, short bouts of standing and physical activity between periods of sedentary activity, even in physically active adults. Behaviorally based exercise interventions, the use of behavior change strategies, supervision by an experienced fitness instructor, and exercise that is pleasant and enjoyable can improve adoption and adherence to prescribed exercise programs. Educating adults about and screening for signs and symptoms of CHD and gradual progression of exercise intensity and volume may reduce the risks of exercise. Consultations with a medical professional and diagnostic exercise testing for CHD are useful when clinically indicated but are not recommended for universal screening to enhance the safety of exercise.

/pdf/quantity-and-quality-of-exercise-for-developing-and-1fohxlhqop.pdf

Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory, Musculoskeletal, and Neuromotor Fitness in Apparently Healthy Adults: Guidance for Prescribing Exercise

Food intake is regulated by the hypothalamus, including the melanocortin and neuropeptide Y (NPY) systems in the arcuate nucleus. The NPY Y2 receptor (Y2R), a putative inhibitory presynaptic receptor, is highly expressed on NPY neurons in the arcuate nucleus, which is accessible to peripheral hormones. Peptide YY3-36 (PYY3-36), a Y2R agonist, is released from the gastrointestinal tract postprandially in proportion to the calorie content of a meal. Here we show that peripheral injection of PYY3-36 in rats inhibits food intake and reduces weight gain. PYY3-36 also inhibits food intake in mice but not in Y2r-null mice, which suggests that the anorectic effect requires the Y2R. Peripheral administration of PYY3-36 increases c-Fos immunoreactivity in the arcuate nucleus and decreases hypothalamic Npy messenger RNA. Intra-arcuate injection of PYY3-36 inhibits food intake. PYY3-36 also inhibits electrical activity of NPY nerve terminals, thus activating adjacent pro-opiomelanocortin (POMC) neurons. In humans, infusion of normal postprandial concentrations of PYY3-36 significantly decreases appetite and reduces food intake by 33% over 24 h. Thus, postprandial elevation of PYY3-36 may act through the arcuate nucleus Y2R to inhibit feeding in a gut–hypothalamic pathway.

BRIEF COMMUNICATION ARISING: Gut hormone PYY3-36 physiologically inhibits food intake

Skeletal muscle has recently been identified as an endocrine organ. It has, therefore, been suggested that cytokines and other peptides that are produced, expressed, and released by muscle fibers and exert paracrine, autocrine, or endocrine effects should be classified as "myokines." Recent research demonstrates that skeletal muscles can produce and express cytokines belonging to distinctly different families. However, the first identified and most studied myokine is the gp130 receptor cytokine interleukin-6 (IL-6). IL-6 was discovered as a myokine because of the observation that it increases up to 100-fold in the circulation during physical exercise. Identification of IL-6 production by skeletal muscle during physical activity generated renewed interest in the metabolic role of IL-6 because it created a paradox. On one hand, IL-6 is markedly produced and released in the postexercise period when insulin action is enhanced but, on the other hand, IL-6 has been associated with obesity and reduced insulin action. This review focuses on the myokine IL-6, its regulation by exercise, its signaling pathways in skeletal muscle, and its role in metabolism in both health and disease.

/pdf/muscle-as-an-endocrine-organ-focus-on-muscle-derived-3c7h8gsq1u.pdf

Muscle as an endocrine organ: focus on muscle-derived interleukin-6.

ContextThe scarcity of data addressing the health effects of popular diets
is an important public health concern, especially since patients and physicians
are interested in using popular diets as individualized eating strategies
for disease prevention.ObjectiveTo assess adherence rates and the effectiveness of 4 popular diets (Atkins,
Zone, Weight Watchers, and Ornish) for weight loss and cardiac risk factor
reduction.Design, Setting, and ParticipantsA single-center randomized trial at an academic medical center in Boston,
Mass, of overweight or obese (body mass index: mean, 35; range, 27-42) adults
aged 22 to 72 years with known hypertension, dyslipidemia, or fasting hyperglycemia.
Participants were enrolled starting July 18, 2000, and randomized to 4 popular
diet groups until January 24, 2002.InterventionA total of 160 participants were randomly assigned to either Atkins
(carbohydrate restriction, n=40), Zone (macronutrient balance, n=40), Weight
Watchers (calorie restriction, n=40), or Ornish (fat restriction, n=40) diet
groups. After 2 months of maximum effort, participants selected their own
levels of dietary adherence.Main Outcome MeasuresOne-year changes in baseline weight and cardiac risk factors, and self-selected
dietary adherence rates per self-report.ResultsAssuming no change from baseline for participants who discontinued the
study, mean (SD) weight loss at 1 year was 2.1 (4.8) kg for Atkins (21 [53%]
of 40 participants completed, P = .009),
3.2 (6.0) kg for Zone (26 [65%] of 40 completed, P = .002),
3.0 (4.9) kg for Weight Watchers (26 [65%] of 40 completed, P < .001), and 3.3 (7.3) kg for Ornish (20 [50%] of 40
completed, P = .007). Greater effects were
observed in study completers. Each diet significantly reduced the low-density
lipoprotein/high-density lipoprotein (HDL) cholesterol ratio by approximately
10% (all P<.05), with no significant effects on
blood pressure or glucose at 1 year. Amount of weight loss was associated
with self-reported dietary adherence level (r = 0.60; P<.001) but not with diet type (r = 0.07; P = .40). For
each diet, decreasing levels of total/HDL cholesterol, C-reactive protein,
and insulin were significantly associated with weight loss (mean r = 0.36, 0.37, and 0.39, respectively) with no significant
difference between diets (P = .48, P = .57, P = .31,
respectively).ConclusionsEach popular diet modestly reduced body weight and several cardiac risk
factors at 1 year. Overall dietary adherence rates were low, although increased
adherence was associated with greater weight loss and cardiac risk factor
reductions for each diet group.

https://jamanetwork.com/journals/jama/articlepdf/200094/JOC40214.pdf

Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial.

Mounting evidence has firmly established that low levels of cardiorespiratory fitness (CRF) are associated with a high risk of cardiovascular disease, all-cause mortality, and mortality rates attributable to various cancers. A growing body of epidemiological and clinical evidence demonstrates not only that CRF is a potentially stronger predictor of mortality than established risk factors such as smoking, hypertension, high cholesterol, and type 2 diabetes mellitus, but that the addition of CRF to traditional risk factors significantly improves the reclassification of risk for adverse outcomes. The purpose of this statement is to review current knowledge related to the association between CRF and health outcomes, increase awareness of the added value of CRF to improve risk prediction, and suggest future directions in research. Although the statement is not intended to be a comprehensive review, critical references that address important advances in the field are highlighted. The underlying premise of this statement is that the addition of CRF for risk classification presents health professionals with unique opportunities to improve patient management and to encourage lifestyle-based strategies designed to reduce cardiovascular risk. These opportunities must be realized to optimize the prevention and treatment of cardiovascular disease and hence meet the American Heart Association's 2020 goals.

Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign: A Scientific Statement From the American Heart Association.

Physical activity and exercise are key components of energy expenditure and therefore of energy balance. Changes in energy balance alter fat mass. It is therefore reasonable to ask: What are the li...

Physical activity and exercise in the regulation of human adipose tissue physiology

The causal role of breakfast in energy balance and health: a randomized controlled trial in obese adults

The aim of this study was to examine the impact of prolonged intermittent high-intensity shuttle running on soreness and markers of muscle damage. Sixteen males took part in the study, half of whom were assigned to a running group and half to a resting control group. The exercise protocol involved 90 min of intermittent shuttle running and walking (Loughborough Intermittent Shuttle Test: LIST), reflecting the activity pattern found in multiple-sprint sports such as soccer. Immediately after exercise, there was a significant increase (P< 0.05) in serum activities of creatine kinase and aspartate aminotransferase, and values remained above baseline for 48h(P< 0.05). Median peak activities of creatine kinase and aspartate aminotransferase occurred 24h post-exercise and were 774 and 43 U.l-1, respectively. The intensity of general muscle soreness, and in the specific muscles investigated, was greater than baseline for 72h after the shuttle test (P < 0.05), peaking 24–48h post-exercise (P< 0.05). Muscle sorene...

Muscular soreness following prolonged intermittent high-intensity shuttle running.

The aim of the present study was to investigate whether 2 weeks of vitamin C supplementation affects recovery from an unaccustomed bout of exercise. Sixteen male subjects were allocated to either a placebo (P; n = 8) or vitamin C group (VC; n = 8). The VC group consumed 200 mg of ascorbic acid twice a day, whereas the P group consumed identical capsules containing 200 mg of lactose. Subjects performed a prolonged (90-min) intermittent shuttle-running test 14 days after supplementation began. Post-exercise serum creatine kinase activities and myoglobin concentrations were unaffected by supplementation. However, vitamin C supplementation had modest beneficial effects on muscle soreness, muscle function, and plasma concentrations of malondialdehyde. Furthermore, although plasma interleukin-6 increased immediately after exercise in both groups, values in the VC group were lower than in the P group 2 hours after exercise (p < .05). These results suggest that prolonged vitamin C supplementation has some modest beneficial effects on recovery from unaccustomed exercise.

Prolonged vitamin C supplementation and recovery from demanding exercise.

Second-order ordinary differential equations of the Numerov type (no first derivative and the given function linear in the solution) are common in physics, but little discussion is devoted to the special first step that is needed before one can apply the general algorithm. We give an explicit algorithm to calculate the first point of the solution with an accuracy appropriate to that obtained with the general algorithm. © 1997 American Institute of Physics.

Dylan Thompson

Papers

Physical activity and exercise in the regulation of human adipose tissue physiology

The causal role of breakfast in energy balance and health: a randomized controlled trial in obese adults

Muscular soreness following prolonged intermittent high-intensity shuttle running.

Prolonged vitamin C supplementation and recovery from demanding exercise.

Getting started with Numerov's method