Resistance Training and Quality of Life Among Younger and Older Adults

Older adults are at risk for sarcopenia, which can lead to reduced physical function, physical activity, and quality of life (QoL). PURPOSE: To determine the effects of aging and sedentary behavior on risk for sarcopenia, the purpose was to compare resistance trained and nonresistance trained younger and older adults on two sarcopenia-related outcomes: QoL and physical activity level (PA). METHODS: Younger (23.8 ± 0.4) and older (68.5 ± 1.2) healthy adults were categorized into 4 groups: young trained (YT: n = 22), young not trained (YNT: n = 16), old trained (OT: n = 17), and old not trained (ONT: n = 21). Resistance trained participants trained ≥ 2X per week, for the past ≥ 6 months. Participants completed a survey to assess health-related QoL, using the Sarcopenia and Quality of Life Questionnaire (SarQoL), and PA, using the Leisure Time Exercise Questionnaire (LTEQ). The SarQoL provides a total QoL score based on 7 dimensions. We were interested in total QoL and the following 3 dimensions: physical and mental health, functionality, and activities of daily living (ADLs). Scores range from 0 (worst health) to 100 (best health). The LTEQ provides a score for PA units, based on vigorous, moderate, and light PA in the past week, with higher scores indicating more PA. ANOVAs were used to determine group differences for each variable, p ≤ 0.05. Data are reported as mean ± SE. RESULTS: Group differences emerged for all variables (p ≤ 0.05). For total QoL, YT (94.5 ± 1.4) was significantly higher than all other groups (YNT: 86.4 ± 1.6, p \u3c 0.001; OT: 87.1 ± 1.6, p = 0.001; ONT: 81.9 ± 1.4, p \u3c 0.001). OT (p = 0.017) and YNT (p = 0.039) were significantly higher than ONT. For physical and mental health, YT (94.2 ± 2.4) was significantly higher than all groups (YNT: 82.2 ± 2.8, p = 0.002; OT: 85.8 ± 2.7, p = 0.022; ONT: 77.9 ± 2.4, p \u3c 0.001). OT was significantly higher than ONT (p = 0.035). For functionality (e.g., balance, climbing stairs), YT (97.5 ± 1.4) again was significantly higher than the other groups (YNT: 92.0 ± 1.6, p = 0.012; OT: 88.9 ± 1.6, p \u3c 0.001; ONT: 85.6 ± 1.4, p \u3c 0.001). YNT was significantly higher than ONT (p= 0.004). For ADLs (e.g., difficulty, fatigue, or pain during physical effort), YT (95.4 ± 1.7) was significantly higher than all groups (YNT: 87.3 ± 1.9, p = 0.002; OT: 87.9 ± 1.9, p = 0.004; ONT: 84.7 ± 1.7, p \u3c 0.001). For all QoL variables, OT did not differ from YNT (p \u3e 0.05). For PA, YT (58.5 ± 6.1 AU) had the same activity level as OT (50.0 ± 6.9 AU, p = 0.356). YT was significantly higher than YNT (31.1 ± 7.3 AU, p = 0.005) and ONT (32.4 ± 6.4 AU, p = 0.004). All other group comparisons were not different (p \u3e 0.05). CONCLUSION: Interestingly, OT was similar to YT on PA and similar to YNT on QoL outcomes. Further, OT was higher than ONT on perceptions of physical and mental health and total QoL. These data suggest that resistance training may be an effective modality to improve or maintain QoL as individuals age

Muscular Torque Output During Neuromuscular Electrical Stimulation Following a 4-week Training Intervention in Older Adults

Neuromuscular electrical stimulation (NMES) can be used to induce muscle torque by generating involuntary muscle contractions. If a greater muscular torque and torque maintenance could be induced by NMES training bouts, it may lead to improvements in electrically induced muscular endurance. However, little is known regarding torque output during NMES pre-post training. PURPOSE: The purpose of this study was to determine if a 4-week NMES training intervention would alter involuntary muscular torque output during the NMES protocol in older, healthy adults. METHODS: Eleven older adults (68.7 ± 2.1 years) completed 12 (Day 1 – Day 12), 40-min NMES training sessions of the quadriceps muscles three times a week, over 4-weeks, with the stimulation frequency set at 60 Hz. Maximal voluntary contractions (MVC) were measured pre-training and mid-training. NMES was delivered through stimulation electrodes placed on the quadriceps muscles and torque output was recorded during the training sessions. Stimulation intensity was set to generate muscular torque output to meet a target representing 15% MVC and was adjusted every 5 minutes to achieve target torque. During each training session, 96 total contractions were generated during the NMES protocol. For Day 1 and Day 12, mean torque, peak torque, and torque time integral (TTI) were measured for each contraction and were then normalized to the pre-training MVC for Day 1 and mid-training MVC for Day 12. The overall mean of the 96 contractions was then calculated for each torque parameter. Sum of TTI (STTI) was calculated by summing the normalized TTI for all contractions. The average stimulation intensity was recorded, and the mean was calculated for each day. Paired sample t-tests were used to test for differences between Days (Day 1 and Day 12) for torque parameters and stimulation intensity. Statistical significance was set at p ≤ 0.05. RESULTS: TTI (Day 1: 90.5 ± 6.1% MVC vs Day 12: 75.9 ± 9.4% MVC; p = 0.036) and STTI (Day 1: 8,686.4 ± 582.0% MVC vs Day 12: 7,2801.0 ± 903.8% MVC; p = 0.036) were lower on Day 12 compared to Day 1. Additionally, there was a trend toward lower mean torque after training (Day 1: 8.7 ± 0.5% MVC vs Day 12: 7.3 ± 0.9% MVC; p = 0.055). Peak torque was not different between days (Day 1: 12.9 ± 0.6% MVC vs Day 12: 13.0 ± 0.7% MVC; p = 0.859). Stimulation intensity showed a trend toward higher stimulation intensity on Day 12 compared to Day 1 (Day 1: 13.3 ± 0.7 mA vs Day 12: 14.6 ± 1.0 mA, p = 0.10). CONCLUSION: Torque output during the NMES protocol was not improved with NMES training and demonstrated a decrease in some torque parameters. The inability of the muscle to produce similar torque output after training may be due to muscle accommodation to the NMES stimulation with repeated bouts. If the goal is to improve involuntary muscular endurance, allowing for more recovery between NMES sessions and use of a lower stimulation frequency may facilitate greater overall muscular torque output following NMES training

Resistance Training may Mitigate Age-related Decline in Physical Function

Aging is often accompanied with the onset of sarcopenia, defined by low muscle mass, strength, and physical function. Regular resistance exercise may mitigate this loss; however, data are lacking that compare younger and older adults who do and do not perform resistance training for general health on skeletal muscle mass and physical function. PURPOSE: The aim of this study was to identify differences in muscle mass and physical function between younger and older adults who did and did not perform resistance training for general health. METHODS: Healthy younger (23.8 ± 0.4 yrs) and older (68.5 ± 1.2 yrs) men and women (n = 76) who either did or did not regularly participate in resistance training were placed into 4 groups: young trained (YT: n = 22), young not trained (YNT: n = 16), old trained (OT: n = 17), and old not trained (ONT: n = 21). Dual energy x-ray absorptiometry assessed appendicular skeletal muscle mass (SMI). Participants performed 4 physical function tests: stair climb (SC), 30s sit-to-stand (30sSTS), 6-min walk test (6MWT), and timed-up-and-go (TUG). ANOVAs were used to compare groups for all measures, p ≤ 0.05. Data are reported as mean ± SE. RESULTS: Differences were found between groups for SMI, SC, 30sSTS, 6MWT, and TUG (p ≤ 0.05). SMI was higher for YT compared to YNT (p = 0.001), ONT (p \u3c 0.0001) and OT (p = 0.032) (YT: 8.67 ± 0.36 kg/m2, YNT: 7.08 ± 0.23 kg/m2, OT: 7.73 ± 0.29 kg/m2, ONT: 7.11 ± 0.27 kg/m2). SC performance was slower for ONT compared to YT (p \u3c 0.0001), YNT (p \u3c 0.0001), and OT (p = 0.032); however, YT and was faster than OT (p = 0.002) (YT: 2.37 ± 0.05s, YNT: 2.60 ± 0.10s, OT: 2.94± 0.15s, ONT: 3.32 ± 0.16s). For 30sSTS, OT completed more reps than ONT (p \u3c 0.0001) and YNT (p = 0.001). YT completed more reps than YNT (p \u3c 0.0001) and ONT (p \u3c 0.0001) (YT: 22.8 ± 0.5 reps, YNT: 18.4 ± 0.7 reps, OT: 22.1 ± 1.1 reps, ONT: 16.7 ± 0.6 reps). OT (p = 0.001), YT (p \u3c 0.0001), and YNT (p = 0.046) walked farther in the 6MWT compared to ONT, and YT walked farther than YNT (p = 0.048) (YT: 837.0 ± 16.7 yds, YNT: 783.2 ± 14.5 yds, OT: 819.9 ± 23.3 yds, ONT: 728.3 ± 18.9 yds). For TUG, OT (p = 0.001) and YT (p = 0.046) were faster than ONT (YT: 5.81 ± 0.17s, YNT: 5.87 ± 0.25s, OT: 5.31 ± 0.19s, ONT: 6.35 ± 0.21s). 30sSTS, 6MWT and TUG were not different between OT and YT. 6MWT and SC were not different between OT and YNT (p \u3e 0.05). All other comparisons were not significantly different (p \u3e 0.05). CONCLUSION: Resistance trained older adults outperformed their nonresistance trained peers and these data suggest that older adults who engage in regular resistance training may maintain physical function similar to that of younger adults

Predicting Resting Metabolic Rate in Healthy Adults using Body Composition and Circumference Measurements

Measurement of resting metabolic rate (RMR) is an important factor for weight management. Previous research has reported several variables to estimate RMR such as body size, percent fat (%BF), age, and sex; however, little is known regarding the effect of circumference measures in estimating RMR. PURPOSE: The purpose of this study was to develop a model to estimate RMR using waist circumference (WC), an easily obtainable measure, and cross-validate it to previously published models. METHODS:Subjects were 140 adult men and women, ages 18-65 years. RMR was measured through indirect calorimetry, %BF was measured through air displacement plethysmography, and fat mass and fat-free mass were determined from %BF and weight. Other variables collected were: weight, height, age, sex, ethnicity, body mass index, WC, hip circumference, waist-to-hip ratio, waist-to-height ratio, and %BF estimated from bioelectrical impedance analysis. Subjects were randomly divided into derivation and cross-validation samples. A multiple regression model was developed to determine the most accurate estimation of RMR in the derivation sample. The cross-validation sample was used to confirm the accuracy of the model and to compare the accuracy to published models. RESULTS:The best predictors for estimating RMR were body weight, r = 0.70, p= 0.031, age, r = -0.30, p= 0.012, and sex, r = 0.51, p= 0.018. Other factors failed to account for significant variation in the model. The derived equation for estimating RMR is: RMR (kcal/day) = 843.11 + 8.77(weight) – 4.23(age) + 228.54(sex, M = 1, F = 0), R2= 0.68, SEE = 173 kcal/day. Cross-validation statistics were: R2= 0.54, p £0.05, SEE = 199 kcal/day, and total error = 198 kcal/day. In published models, R2ranged from 0.47 to 0.57, SEE ranged from 192 to 213 kcal/day, and total error ranged from 212 to 1311 kcal/day. CONCLUSIONS:Cross-validation to published models for estimating RMR were similar to those of the derived model; however, the total error in the derived equation was lower than any of the previously published models. Several published models considerably overestimate RMR compared to the current model. The results of this study suggest that RMR can be reasonably estimated with easily obtainable measures which allow for estimation and implementation of RMR for weight management in clinical practice

Neuromuscular Electrical Stimulation Effects on Skeletal Muscle Fatigue in Older Adults

Neuromuscular electrical stimulation (NMES) is often used as a rehabilitative modality and evidence has suggested that high frequencies of NMES may elicit increases in muscle strength. However, little is known regarding the effects of a high-frequency NMES intervention on voluntary skeletal muscle fatigue. PURPOSE: The aim of this study was to determine the effect of a 4-week high-frequency NMES intervention on voluntary muscular fatigue and changes in neuromuscular activation patterns of the quadriceps during voluntary fatiguing muscle contractions in older adults. METHODS: Seventeen healthy, older adults (68.8 ± 1.8 years old) participated in the study (NMES: n = 12; SHAM: n = 5). Each participant was seated on an isokinetic dynamometer, and a 40-min NMES treatment was applied to the quadriceps muscles of each leg 3x/week for 4 weeks with the stimulation frequency set at 60 Hz. Stimulation intensity was set to achieve 15% of knee extension maximal voluntary contraction (MVC). Those in the SHAM group underwent the same treatment procedures but did not receive the NMES treatment. All subjects performed maximal voluntary contractions (MVC) and an intermittent knee extension isometric submaximal voluntary fatigue task at 50% MVC until the fatigue criteria were met for pre-post testing. Surface electromyography (sEMG) of the vastus lateralis (VL) and vastus medialis (VM) muscles were recorded during the fatigue task to examine changes in muscle activation. EMG data were quantified for root mean square (RMS) EMG and reported as a percent rate of change over the duration of the fatigue task and median frequency (MF) is reported as the average MF during the fatigue task. Repeated measures ANOVAs were used to determine differences pre-post NMES for muscular endurance time, MVC and EMG measures. Statistical significance was set at p \u3c 0.05. RESULTS: MVC increased pre-post NMES in the NMES group (117.1 ± 8.7 Nm vs 127.6 ± 11.1 Nm, p = 0.049; pre- and post-training, respectively) with no change in SHAM (p = 0.96). Muscular endurance time did not change pre-post NMES (NMES: 159.3 ± 20.1s vs 141.9 ± 21.2s, p = 0.29; SHAM: 242.2 ± 43.3s vs 202.9 ± 23.3s, p = 0.13; pre- and post-training, respectively). RMS EMG rate of change did not change following NMES treatment (NMES: VL: 16.6 ± 3.6% vs 18.8 ± 10.4%, p = 0.84; VM: 11.4 ± 2.1% vs 19.6 ± 5.5%, p = 0.15; SHAM: VL: 7.8 ± 1.6% vs 7.1 ± 3.0%, p = 0.81; VM: 7.1 ± 3.3% vs 5.9 ± 2.2%, p = 0.55; pre- and post-training, respectively). Also, there was no difference in MF EMG with NMES training (NMES: VL: 77.6 ± 4.1 Hz vs 74.9 ± 3.6 Hz, p = 0.13; VM: 72.5 ± 2.4 Hz vs 72.6 ± 2.2 Hz, p = 0.97; SHAM: VL: 79.3 ± 3.4 Hz vs 80.2 ± 4.9 Hz, p = 0.85; VM: 76.9 ± 3.7 Hz vs 83.9 ± 5.1 Hz, p = 0.12; pre- and post-training, respectively). CONCLUSION: Treatment with high-frequency NMES did not improve muscle endurance or related EMG parameters. It is possible that NMES induced adaptations may be frequency-specific and that high-frequency NMES may not be efficacious when the goal is to improve skeletal muscle endurance

Improvement in Physical Function and Quality of Life in Older Adults Following 4 Weeks of Neuromuscular Electrical Stimulation

Older adults often suffer from sarcopenia, the age-related loss of muscle mass and strength, which negatively impacts physical function and quality of life (QoL). Neuromuscular electrical stimulation (NMES) is frequently used in physical rehabilitation as a muscle strengthening modality; however, little research exists on QoL outcomes in response to NMES. PURPOSE: The aim of this study was to determine changes in QoL and physical function in older adults after 4 weeks of NMES. METHODS: Ten healthy, older adults participated in the study (67.8 ± 2.1 years-old). Each participant was seated on an isokinetic dynamometer with the knee positioned at 60°, and a 40-min NMES treatment was applied to the quadriceps muscles of each leg 3 times per week for 4 weeks. Stimulation frequency was set at 60 Hz with repeated cycles of 10s on and 15s off. Stimulation intensity was set to achieve 15% of each participant’s maximal voluntary contraction (MVC) and was increased every 5 minutes if the torque was below 15% MVC. Each subject was given a pre and post intervention survey assessing indicators of QoL: self-efficacy for physical function (0-100 scale), perceived competence in physical domains (e.g., strength, endurance, coordination, 1-6 scale), physical self-concept (1-6 scale), and intention to be physically active (1-7 scale). Physical function of the lower body was assessed pre and post intervention with a timed up and go test (TUG). Paired sample t-tests were used to test for differences over time (pre, post) for TUG and QoL dimensions (significance set at p \u3c 0.05). Cohen’s d was calculated for effect size. RESULTS: Perceived coordination significantly increased with a medium effect size (5.10 ± .0.16 vs 5.38 ± 0.17, p = 0.03, d = 0.55), pre vs post, respectively. The following QoL dimensions showed a statistically non-significant increase with a small effect size: intention to be physically active (6.08 ± 0.58 vs 6.68 ± 0.22, p = 0.33, d = 0.48), self-efficacy (95.61 ± 2.19 vs 97.37 ± 1.40, p = 0.10, d = 0.31), and endurance (3.57 ± 0.33 vs 3.77 ± 0.19, p = 0.43, d = 0.24). Two dimensions trended toward improvement: physical self-concept (4.57 ± 0.35 vs 4.77 ± 0.30, p = 0.37, d = 0.19) and physical activity (4.08 ± 0.45 vs 4.30 ± 0.31, p = 0.36, d = 0.19. There was a significant decrease in time to complete the TUG (8.77 ± 0.59s vs 7.71 ± 0.43s, p = 0.004, d = 0.63). CONCLUSION: TUG times and coordination showed significant improvement while other QoL dimensions trended toward improvement after 4 weeks of NMES. Enhanced physical function subsequent to NMES treatment may contribute to improved overall QoL by increasing confidence to perform physical activities, and may thereby counter the risk of sarcopenia

Psychological and Physical Response to Neuromuscular Electrical Stimulation

Neuromuscular electrical stimulation (NMES) is commonly used to improve muscle function in physical rehabilitation settings. However, reasons for limited use as an alternative to voluntary exercise may be due to lack of familiarity and perceived discomfort during treatment. PURPOSE: The purpose of this study was to determine attitude toward NMES exercise and perceived pain and muscle soreness experienced from NMES exercise with increasing stimulation intensity. METHODS: Thirty healthy adults (age: 23.6 ± 0.5 years) who had not experienced electrical stimulation within the last year completed the study. Repetitive, intermittent stimulation of 10 seconds on and 15 seconds off was applied to the quadriceps muscles for 60 minutes with the stimulation frequency set at 60 Hz. Stimulation intensity was increased every 5 min throughout the course of the intervention to achieve a target torque of 15% maximal voluntary contraction as measured by an isokinetic dynamometer. During the NMES application, participants rated the pain they experienced using a standard pain scale (0-10 scale: 0 = no pain; 10 = most pain possible) at minute 0, 15, 30, 45, and 55 of the treatment. Participants were also asked to rate muscle soreness felt 48 hours after exercise (0-10 scale: 0 = no soreness; 10 = greatest soreness possible). A survey on attitude toward NMES exercise (e.g., useful, pleasant, beneficial) was administered pre and post NMES on a 1-7 scale (e.g., 1 = useless; 7 = useful). Repeated measures analysis of variance (ANOVA) was used to test statistical differences between scores over time. Data are reported as mean ± SE. RESULTS: Attitude toward NMES exercise was high and did not change pre-post exercise (pre: 6.2 ± 0.1, post: 6.1 ± 0.2, p = 0.21). Reported pain during NMES was low and was not different across time points (0 min: 2.1 ± 0.4, 15 min: 2.7 ± 0.4, 30 min: 2.6 ± 0.4, 45 min: 2.9 ± 0.4, 55 min: 2.5 ± 0.4, p = 0.126). Muscle soreness remained elevated 48-hours post-NMES (3.5 ± 0.593, p \u3c 0.001). CONCLUSION: Pain reported during NMES was low and did not increase as stimulation intensity increased. Attitudes toward NMES sessions were relatively high and were unchanged after exercise, indicating that any pain and soreness experienced did not change participants’ attitude regarding the benefits of NMES exercise

Effect of Neuromuscular Electrical Stimulation Training on Control of Involuntary Muscular Torque and Stimulation Intensity in Older Adults

International Journal of Exercise Science 16(3): 482-496, 2023. The purpose of this study was to examine the effects of a 4-week neuromuscular electrical stimulation (NMES) training regimen on involuntary torque output and electrical stimulation intensity in older adults. Twelve older adults (ages: 68.4 ± 6.5 years; men: n = 6, women: n = 6; weight: 158.6 ± 27.3 lbs; height: 65.2 ± 2.1 in) received submaximal intensity NMES to the quadriceps for 4 weeks to determine training-related changes in stimulation intensity and involuntary control of muscular torque during the NMES protocol. Two-way repeated measures ANOVAs were used to compare torque parameters and stimulation intensity between days and across protocol time bins. After training, stimulation intensity and torque increased over the course of the NMES protocol, while torque decreased during the protocol pre-training. These results suggest that muscular endurance of involuntary muscle contraction is increased with NMES training, and that stimulation intensity should be increased throughout the course of training to augment muscular torque output