Megavolt bremsstrahlung measurements from linear induction accelerators demonstrate possible use as a FLASH radiotherapy source to reduce acute toxicity.

Recent studies indicate better efficacy and healthy tissue sparing with high dose-rate FLASH radiotherapy (FLASH-RT) cancer treatment. This technique delivers a prompt high radiation dose rather than fractional doses over time. While some suggest thresholds of > 40 Gy s with a maximal effect at > 100 Gy s, accumulated evidence shows that instantaneous dose-rate and irradiation time are critical.

The effects of a novel bicarbonate loading protocol on serum bicarbonate concentration: a randomized controlled trial.

Background: Previous studies have shown that sodium bicarbonate ingestion may enhance intense exercise performance, but may also cause severe gastrointestinal distress. The purpose of this study was to determine whether a modified sodium bicarbonate (SB) ingestion protocol would elevate serum bicarbonate concentration more than previous methods without causing gastrointestinal distress.

Methods: In randomized order, seven (5 men, 2 women) elite middle-distance runners ingested either placebo, Modified SB (600 mg·kg over 19.

Leg strength declines with advancing age despite habitual endurance exercise in active older adults.

Age-associated loss of muscle mass (sarcopenia) and strength (dynapenia) is associated with a loss of independence that contributes to falls, fractures, and nursing home admissions, whereas regular physical activity has been suggested to offset these losses. The purpose of this study was to evaluate the effect of habitual endurance exercise on muscle mass and strength in active older adults. A longitudinal analysis of muscle strength (≈4.

Sustainability of critical power determined by a 3-minute all-out test in elite cyclists.

Critical power (CP) is a theoretical workload representative of an athlete's maximal sustainable pace. Recent research has validated a 3-minute all-out test on a cycle ergometer for determining CP; however, few studies have investigated the sustainability of CP using this test. The purpose of this study was to determine the sustainability of CP established during the 3-minute test and the determinants of sustainability.

The effects of a walking exercise program on fall-related fitness, bone metabolism, and fall-related psychological factors in elderly women.

The purpose of this study was to determine the effects of a 3-month walking exercise program with ankle weights on fall-related fitness, bone metabolism, and fall-related psychological factors. Fall-related fitness was determined from strength, balance, agility, aerobic endurance, muscle mass, and fat mass measures. Bone metabolism was measured using bone density, hormones, and biochemical markers.

Anthropometric and lifestyle associations of bone mass in healthy pre-menopausal Mexican and Asian American women.

Few studies have established the lifestyle predictors of peak bone mineral density (BMD) in Mexican-American (MA) and Asian-American (AA) women. Pre-menopausal MA (n = 48) and AA (n = 58) women aged 30-45 years old were tested for BMD, body composition, aerobic fitness, and muscle function. Socio-demographic characteristics, health status, prevalence of osteoporosis risk factors, physical activity, and diet were determined via questionnaire.

Longitudinal change in coronary heart disease risk factors in older runners.

Background: it is currently not clear how coronary heart disease (CHD) risk factors change over time in chronic exercisers. Therefore, the purpose of this study is to describe the longitudinal change in CHD risk factors in chronically endurance-trained men and women, and to determine the exercise and nutritional factors associated with those respective changes.

Methods And Results: ninety-one middle-aged runners (56 male, 35 female) were tested on two occasions approximately 10 years apart (aged 50.

Chronic exercise and skeletal muscle power in older men.

We sought to determine the effects of age and chronic exercise on muscle power in older males. We examined 32 older males 60-74 years of age and grouped as sedentary (CON, n = 11), chronic endurance trained (ET, n = 10), and chronic endurance trained + resistance training (ET + RT, n = 11). Exercise history was obtained by questionnaire.

Endurance exercise and leg strength in older women.

Quadriceps strength and mass peak in the third decade of life, plateau, and then decline from the fifth decade on. To examine the influence of chronic endurance training and age on lean mass and leg strength, women runners (n = 62, age 43-69 years) and sedentary participants (n = 33, age 43-66 years) were divided into 40-, 50-, and 60-year age groups. Absolute isokinetic concentric torque did not differ between runners and sedentary women (97.

Musculoskeletal adaptations to 16 weeks of eccentric progressive resistance training in young women.

We investigated the musculoskeletal adaptations and efficacy of a whole-body eccentric progressive resistance-training (PRT) protocol in young women. Subjects (n = 37; mean age, 24.3) were randomly assigned to one of 3 groups: high-intensity eccentric PRT (HRT), low-intensity eccentric PRT (LRT), or control.

An estimate of physical activity prevalence in a large population-based cohort.

Purpose: The purpose of this study was to describe the prevalence of self-reported moderate and vigorous physical activity (PA) among 40,261 native Californians in relation to age, gender, education, race/ethnicity, and self-reported disease risk factors.

Methods: Subjects, from the California Twin Program, completed a questionnaire that included three PA questions and were categorized by their level of PA: moderate and vigorous PA sufficient to meet CDC and ACSM guidelines. The relationship between demographic variables, chronic disease risk factors, and meeting the PA guidelines are reported.

Endurance training delays age of decline in leg strength and muscle morphology.

Purpose: It has been reported that maximal strength peaks at approximately 30 yr of age, plateaus, and remains relatively stable for the next 20 yr, with an age-related decline in strength becoming significant after age 50. Much of the research attributes this decrease in peak force to age-associated reductions in muscle mass, with a selective atrophy and reduction in Type II fiber area and number being the primary factors. The influence that chronic endurance training has upon age-associated changes in muscular strength and muscle morphology has been largely undetermined.

Exercise and the master athlete--a model of successful aging?

Exercise as a therapeutic or prophylactic measure is a topic of particular interest in sarcopenia research. Clearly, exercise can be effectively utilized in the treatment of sarcopenia to recover muscle mass and muscle function in older adults. However, perhaps a more important question is the role of exercise in the prevention of age-related decrements in physiological capacities and function.

Longitudinal analysis of lactate threshold in male and female master athletes.

Purpose: The lack of relationship between lactate threshold (LT) and running performance in older runners, and the increase in LT with age, has not been previously studied in a longitudinal design. We evaluated the cross-sectional and longitudinal changes in LT with age and compared the changes in LT with changes in performance variables.

Methods: Fifty-one male and 23 female runners (39-77 yr) performed two graded treadmill exercise tests with minute-by-minute venous blood lactate analysis, separated by 5.

Five-year maintenance of bone mineral density in women master runners.

Purpose: Prior research has suggested that chronic running may not prevent age-related bone loss in women and may inhibit the influence of hormone replacement therapy (HRT) on bone. The purpose of this study was to longitudinally determine the effect of chronic running exercise alone, and in conjunction with HRT, on bone mineral density (BMD) in premenopausal and postmenopausal women.

Methods: Forty-one women runners were tested an average of 4.

Maintenance of BMD in older male runners is independent of changes in training volume or VO(2)peak.

Background: The results of several recent research studies have questioned the benefit of chronic running in reducing the risk of developing osteoporosis. These negative conclusions are based upon the findings that runners, in general, are not different from controls with regard to their bone mineral density (BMD). This has led one to speculate that the value of weight-bearing exercise might be related to its ability to maintain bone mass or, perhaps, decrease the expected rates of loss.