This Q&A was originally published in the Winter 2020 issue of American Fitness Magazine.
What’s the latest on steps per day to support longevity, the best aerobic exercise programs for metabolic syndrome and improving muscle response to protein ingestion?
DOES TAKING 10,000 STEPS PER DAY REDUCE MORTALITY RISK FOR OLDER WOMEN?
Steps and health—specifically, mortality risk—have long been associated with one another. However, the popular threshold of “10,000 steps per day” may not be the best standard for reducing the likelihood of living a shorter life.
Using accelerometer data from 16,741 women between the ages of 66 and 78, researchers looked at steps per day and walking speed while adjusting for other variables associated with mortality risk. Participants were categorized into quartiles, based on steps per day, and median daily step counts for each quartile were recorded as 2,718; 4,363; 5,905; and 8,442. The mean step count per day for all participants was 5,499.
The researchers concluded that significant reductions in mortality risk began at 3,000 steps per day and plateaued around 7,500 steps per day. More specifically, 4,400 steps per day led to a 41% reduction in mortality risk compared with lower step counts. Results regarding the effects of walking speed were not as clear, perhaps because of the small number of participants stepping at a fast rate.
Reference: Lee, I-M., et al. 2019. Association of step volume and intensity with all-cause mortality in older women. JAMA Internal Medicine, 179 (8), 1105–12.
WHAT LEVEL OF AEROBIC EXERCISE TRAINING IS BEST FOR ADDRESSING METABOLIC SYNDROME?
The prevalence of metabolic syndrome (MetS) is rising as rates of physical inactivity increase. To be diagnosed with MetS, an individual must have three of the following four health concerns: central obesity, dyslipidemia, hypertension and hyperglycemia. Improvements in cardiorespiratory fitness (CRF) have been associated with improved markers of MetS; furthermore, research has shown that high-intensity interval training (HIIT) leads to improvements in CRF sooner than moderate-intensity continuous training (MICT).
A study conducted in Spain attempted to determine if 16 weeks of 1:1.5 HIIT (1HIIT), 4:3 HIIT (4HIIT) or MICT was best for improving CRF in 99 men and women meeting criteria for MetS, compared with a 22-person control group. Exercise durations for 1HIIT, 4HIIT and MICT were 35, 43 and 50 minutes, respectively. Along with CRF, the following variables were analyzed before, during and after the intervention: body weight, waist circumference, blood pressure, blood glucose, insulin, and lipids (triglycerides and HDL-c).
At the study’s conclusion, all three training groups showed improvements in CRF and blood pressure. In addition, the 4HIIT and 1HIIT groups saw decreases in waist circumference, and the 4HIIT and MICT groups reported reduced MetS scores. Weight loss occurred only in the 4HIIT group, and lower triglycerides only in the MICT group. The 1HIIT group did not experience a drop in MetS score; rather, blood glucose increased in this group.
Since 4HIIT and MICT were matched for energy expenditure, training volume could be more significant than intensity or exercise type in promoting health among individuals with MetS.
Reference: Morales-Palomo, F., et al. 2019. Effectiveness of aerobic exercise programs for health promotion in metabolic syndrome. Medicine & Science in Sports & Exercise, 51 (9), 1876–83.
DOES CONSUMING LEUCINE WITH PROTEIN HELP BUILD MUSCLE?
In addition to correlating muscle loss, or sarcopenia, with aging, research has shown that muscle doesn’t respond as favorably to protein consumption and physical activity in older adults compared with younger ones. As a result, building muscle requires more protein consumption. Adding leucine—a powerful amino acid—to protein is thought to improve the muscle-building process.
In a study, 24 men, ages 66–68, performed a single session of resistance training in two groups: participants who consumed 15 grams of protein post-exercise and those who consumed the same amount of protein plus 1.5 g of leucine. After a 10-minute warmup, the men performed four exercises—two lower-body (leg press, leg extension) and two upper-body (lat pulldown, chest press)—at ≥50%–80% of one-repetition maximum during working sets and during 2 or more sets with 8 or more reps (recommended for muscle hypertrophy). Before and after the training, the researchers collected blood samples and muscle biopsies to determine muscle-building rates.
Results revealed increases in insulin and leucine concentrations following protein ingestion in both groups. While some muscle- building markers improved in the group that consumed leucine along with protein, other markers did not show any difference. However, it is reasonable to suggest that adding leucine to protein may improve muscle building in older adults following resistance exercise.
Reference: Holwerda, A.M., et al. 2019. Leucine coingestion augments the muscle protein synthetic response to the ingestion of 15 g of protein following resistance exercise in older men. American Journal of Physiology, Endocrinology, and Metabolism, 317 (3), E473–82.
