The Effects of Power Training Frequency on Muscle Power and Functional Performance in Older Women: A Randomized Controlled Trial.

ABSTRACT: Katsoulis, K and Amara, CE. The effects of power training frequency on muscle power and functional performance in older women: a randomized controlled trial. J Strength Cond Res 37(11): 2289-2297, 2023-Low-intensity power training (PT) has emerged as an effective method for improving muscle power and functional performance in older adults. However, effects of low training frequencies are less understood and could expand the repertoire of exercise prescription, particularly in older women who experience greater functional disability with age compared with men. This study investigated the impact of frequency of low-intensity (40% of 1 repetition maximum, 1RM) PT on lower-body power and functional performance in healthy older women. Women (74 ± 4 years) were randomized to 12 weeks of PT of 1 (PT1, n = 14), 2 (PT2, n = 17), or 3 (PT3, n = 17) d·wk -1 or wait control (CON, n = 15). Measures included leg press 1RM, knee extension power (KEP), and functional performance (stair climb power, stair climb time, 30-second chair stands, 400-m walk, Short Physical Performance Battery). There were no differences between the frequency of training in changes in leg press 1RM, KEP, or functional performance after 12 weeks. Pre-post data for individual training groups revealed that leg press 1RM improved in all PT groups (20-33%, p < 0.05). Furthermore, KEP improved in PT2 and PT3 by 10 and 12%, respectively, and all PT groups improved in the 30-second chair stands and Short Physical Performance Battery (6-22%), whereas PT1 and PT3 improved in the 400-m walk and PT2 improved in stair climb power and stair climb time after training (4-7%, p < 0.05). One to 3 weekly low-intensity PT sessions can improve functional performance, although improvements in both functional performance and power might require 2 or 3 sessions per week in older healthy women.

Reliability of Lower Extremity Muscle Power and Functional Performance in Healthy, Older Women.

Evaluation of the long-term reliability of muscle power and functional performance tests in older, healthy adults is warranted since determining whether performance is consistent over longer durations is more relevant for intervention studies. Objective. To assess the long-term test-retest reliability of measures of muscle power and lower body functional performance in healthy, nonexercising, older women. Methods. Data were derived from a nonexercising control group (n = 18; age = 73.3 (3.4) years; height = 159.6 (7.7) cm; body mass = 69.5 (12.7) kg; BMI = 27.3 (4.8)) of a randomized controlled trial of muscle power training in older women. Participants underwent lower extremity muscle power (Biodex) and functional testing (Short Physical Performance Battery, gait speed, 30-second chair stands, stair climbing, and 400-meter walk) at week 0 (baseline), 9, and 15. Results. For the upper leg, intraclass correlation coefficients (ICCs) were very high for knee extension power (0.90-0.97) and high to very high for knee flexion power (0.83-0.96). For lower-leg power, ICCs were high to very high for plantar flexion and dorsiflexion (0.83-0.96). ICCs for functional performance were moderate to very high (0.64-0.93). Coefficient of variation of the typical error (CVTE) was <10.5% for knee extension/flexion power, 9.9-20.0% for plantar flexion/dorsiflexion power, and 1.9-14.9% for functional performance. Knee extension power and stair climb power demonstrated the highest reliability for muscle power and function, respectively. Mean values did not change over time, with the exception of the chair stands (p < 0.05); however, these changes were not considered clinically meaningful. Conclusions. The current study provides evidence supporting the long-term reliability of performance assessments of muscle power and lower body functional capacity over a period of up to 15 weeks in healthy, older women.

The Effects of High- Versus Low-Intensity Power Training on Muscle Power Outcomes in Healthy, Older Adults: A Systematic Review.

Power training (PT) improves muscle power in older adults; however, intensity recommendations are less clear. A narrative approach was used to compare high- versus low-intensity PT on muscle power (and function) in healthy, older adults. Searches were performed using Medline, Embase, CINAHL, SPORTDiscus, AgeLine, and Scopus. Interventions in which older subjects (60+ years) were instructed to perform the concentric phase "as fast as possible" were included. After searches were performed, a third category of PT (moderate intensity) was included. Evidence from 27 studies (32 PT groups) showed changes in muscle power that averaged 26.8%, 33.4%, and 21.5% for high-, moderate-, and low-intensity PT, respectively, with greater changes with longer training duration and in mildly mobility-limited older adults. Function improved similarly across categories. In conclusion, both low- and high-intensity PT led to clinically significant changes in power and are viable options for improving power and function in older adults.

Tendon length and joint flexibility are related to running economy.

PURPOSE: The purpose of study was to determine whether quadriceps/patella and Achilles tendon length and flexibility of the knee extensors and plantar flexors are related to walking and running economy. METHODS: Twenty-one male distance runners were subjects. Quadriceps/patella and Achilles tendon length were measured by magnetic resonance imaging; body composition was measured DXA; oxygen uptake at rest while seated, walking (3 mph), and running (6 and 7 mph) were measured by indirect calorimetry; knee and ankle joint flexibility were measured by goniometry; and leg lengths were measured by anthropometry while seated. Correlations were used to identify relationships between variables of interest. RESULTS: Net VO2 (exercise VO2 - rest VO2) for walking (NVOWK) and running at 6 and 7 mph (NVO6 and NVO7, respectively) was significantly related to Achilles tendon length (r varying from -0.40 to -0.51, P all < 0.04). Achilles tendon cross section was not related to walking or running economy. Quadriceps/patella tendon length was significantly related to NVO7 (r = -0.43, P = 0.03) and approached significance for NVO6 (r = -0.36, P = 0.06). Flexibility of the plantar flexors was related to NVO7 (+0.38, P = 0.05). Multiple regression showed that Achilles tendon length was independently related to NVO6 and NVO7 (partial r varying from -0.53 to -0.64, all P < 0.02) independent of lower leg length, upper leg length, quadriceps/patella tendon length, knee extension flexibility, or plantarflexion flexibility. CONCLUSIONS: These data support the premise that longer lower limb tendons (especially Achilles tendon) and less flexible lower limb joints are associated with improved running economy.

Diet-induced changes in intra-abdominal adipose tissue and CVD risk in American women.

The aim of the study was to determine what effect weight loss had on intra-abdominal adipose tissue (IAAT) and cardiovascular disease (CVD) risk in 135 premenopausal overweight African-American (AA) and European-American (EA) women matched for BMI. Blood lipids, systolic blood pressure (SBP), diastolic BP (DBP), and IAAT (computed tomography determined) were examined prior to and after an 800 kcal/day diet producing 12 kg-weight loss. Significant decreases in IAAT (approximately 38%), total cholesterol (TC; 3%), low-density lipoproteins (LDLs: 6%), triglycerides (TGs: 27%), cholesterol/high-density lipoprotein ratio (C/HDL ratio: 18%), SBP (3%), and DBP (3%) occurred while HDL increased (16%), following weight loss and 1 month energy balance. Significant interactions between time and race showed that AA women decreased TG and increased HDL proportionately less than EA women. After adjusting for Delta IAAT, none of the CVD variables significantly changed after weight loss with the exception of HDL and C/HDL ratio. After adjusting for Delta LF (leg fat), Delta TC, Delta TG, Delta LDL, and Delta C/HDL ratio were significantly different. Multiple regression showed that independent of each other, Delta IAAT was significantly and positively related to Delta TC (adjusted beta = 0.24) and Delta TG (adjusted beta = 0.47), and Delta LF was negatively related to Delta TC (adjusted beta = -0.19) and Delta TG (adjusted beta = -0.18). Overweight and premenopausal AA and EA women benefitted from weight loss by decreasing IAAT and improving CVD risk. The changes in IAAT were significantly related to blood lipids, but loss of LF seems to be related to reduced improvement in TC and TG. Based on these results, interventions should focus on changes on IAAT.