The human body requires energy to function. Adenosine triphosphate (ATP) is the cellular currency for energy-requiring processes including mechanical work (i.e., exercise). ATP used by the cells is ultimately derived from the catabolism of energy substrate molecules—carbohydrates, fat, and protein. In prolonged moderate to high-intensity exercise, there is a delicate interplay between carbohydrate and fat metabolism, and this bioenergetic process is tightly regulated by numerous physiological, nutritional, and environmental factors such as exercise intensity and duration, body mass and feeding state. Carbohydrate metabolism is of critical importance during prolonged endurance-type exercise, reflecting the physiological need to regulate glucose homeostasis, assuring optimal glycogen storage, proper muscle fuelling, and delaying the onset of fatigue. Fat metabolism represents a sustainable source of energy to meet energy demands and preserve the ‘limited’ carbohydrate stores. Coordinated neural, hormonal and circulatory events occur during prolonged endurance-type exercise, facilitating the delivery of fatty acids from adipose tissue to the working muscle for oxidation. However, with increasing exercise intensity, fat oxidation declines and is unable to supply ATP at the rate of the exercise demand. Protein is considered a subsidiary source of energy supporting carbohydrates and fat metabolism, contributing to approximately 10% of total ATP turnover during prolonged endurance-type exercise. In this review we present an overview of substrate metabolism during prolonged endurance-type exercise and the regulatory mechanisms involved in ATP turnover to meet the energetic demands of exercise.

The aim of the study was to examine the anthropometric measurements, sociodemographics, and lifestyle behaviors among Saudi adolescents relative to sex and physical activity (PA). A random cross-sectional survey conducted on Saudi adolescents from secondary schools in Riyadh, using a multistage stratified cluster sampling technique. Measurements included demographics, weight, height, waist circumference, PA, sedentary behaviors (SB), sleep duration, and dietary habits using a validated questionnaire. A total of 1262 adolescents (16.4 ± 0.95 years; 52.4% males) were studied. Overweight/obesity was more than 40%. Physical inactivity among adolescents was 53%, which indicates some improvement over the past years, especially among females. More than 80% of adolescents had over three hours/day of screen time, with no significant sex differences. Insufficient sleep was highly prevalent with gender differences. A large proportion of the participants did not consume daily breakfast (65.7%), vegetables (73.2%), fruits (84.2%), or milk/dairy products (62.4%), whereas significant proportions of the adolescents consumed sugar-sweetened drinks, fast food, French fries/potato chips, cake/donuts, and chocolates/candy on at least three days or more per week. It was concluded that non-daily intake of breakfast and vegetables was significantly associated with lower PA. The updated information can aid in effectively planning and implementing promotional programs toward improving the lifestyle behaviors of Saudi adolescent.

We examined whether carbohydrate-protein ingestion influences muscle glycogen metabolism during short-term recovery from exhaustive treadmill running and subsequent exercise. Six endurance-trained individuals underwent two trials in a randomized double-blind design, each involving an initial run-to-exhaustion at 70% VO_2max (Run-1) followed by 4-h recovery (REC) and subsequent run-to-exhaustion at 70% VO_2max (Run-2). Carbohydrate-protein (CHO-P; 0.8 g carbohydrate·kg body mass [BM^-1]·h^-1 plus 0.4 g protein·kg BM^-1·h^-1) or isocaloric carbohydrate (CHO; 1.2 g carbohydrate·kg BM^-1·h^-1) beverages were ingested at 30-min intervals during recovery. Muscle biopsies were taken upon cessation of Run-1, postrecovery and fatigue in Run-2. Time-to-exhaustion in Run-1 was similar with CHO and CHO-P (81 ± 17 and 84 ± 19 min, respectively). Muscle glycogen concentrations were similar between treatments after Run-1 (99 ± 3 mmol·kg dry mass [dm^-1]). During REC, muscle glycogen concentrations increased to 252 ± 45 mmol·kg dm^-1 in CHO and 266 ± 30 mmol·kg dm^-1 in CHO-P (p = .44). Muscle glycogen degradation during Run-2 was similar between trials (3.3 ± 1.4 versus 3.5 ± 1.9 mmol·kg dm^-1·min^-1 in CHO and CHO-P, respectively) and no differences were observed at the respective points of exhaustion (93 ± 21 versus 100 ± 11 mmol·kg dm^-1; CHO and CHO-P, respectively). Similarly, time-to-exhaustion was not different between treatments in Run-2 (51 ± 13 and 49 ± 15 min in CHO and CHO-P, respectively). Carbohydrate-protein ingestion equally accelerates muscle glycogen resynthesis during short-term recovery from exhaustive running as when 1.2 g carbohydrate·kg BM^-1·h^-1 are ingested. The addition of protein did not alter muscle glycogen utilization or time to fatigue during repeated exhaustive running.

Physical inactivity among the general population is of great concern in public health.This narrative review aims to identify promising physical activity (PA) public policies based on the best avail...

The concept of health span is an emerging topic in recent years, with a truly palpable relevance to public health. With ageing comes a loss of skeletal muscle mass, strength, and performance, which is termed as sarcopenia. Sarcopenia is a major public health concern and poses a challenge to health-care systems. Modifiable lifestyle factors may be linked to the course of sarcopenia progression. Many countries developed diagnostic tools to accurately detect sarcopenia for its prevention, delay, or treatment. However, to date, there is no sufficient information regarding the status of sarcopenia in Saudi Arabia. The review aims to discuss sarcopenia and relevant updates in research and literature, the association with modifiable lifestyle factors, the implications of sarcopenia in a rapidly developing country such as Saudi Arabia, and the current state and need for research in Saudi Arabia in this domain along with future directions in combating this disease.

Background: Sedentary behaviors (SB) are very prevalent nowadays. Prolonged sitting associates with chronic disease risks and increased mortality even while controlling for physical activity. Objective measurement of SB is costly, requires technical expertise, and is challenging in terms of time and management. Currently, there is no validated self-reported instrument in the Arabic language that assesses SB among individuals and relates sedentary time to social, environmental, and health outcomes. The aim of this research was to develop a multi-item Arabic SB questionnaire (ASBQ). Methods: The ASBQ was developed through an extensive literature review and discussion by the research team (n = 5), then went through content validation (n = 10 experts) and pre-testing using cognitive interviewing procedures (n = 51 respondents, mean (SD) age was 38.3 (18.2) years, and with 49% females). Results: The ASBQ included 13 questions comprising a wide range of sedentary activities. The Arabic SB instrument showed excellent content validity for assessing sedentary time in adolescents and adults with a very high item-level and scale-level content validity index. A kappa statistic, a measure of interrater reliability, was 0.95. The pre-testing showed that the instrument was highly rated by a diverse sample of Saudi adolescents and adults. Conclusion: The ASBQ received excellent acceptance by a panel of experts with promising pre-test results. Further testing of psychometric properties, including test-retest reliability and criterion validity is required.