Acceptance and Feasibility of Seated Elliptical Pedaling to Replace Sedentary Behavior in Older Adults.

The purpose of this study was to explore the feasibility and acceptability of a seated pedaling device to reduce sedentary behavior (SB) in the homes of older adults. METHODS: Each participant (N = 20) was outfitted with an activity monitor and seated pedaling device in the home for 7 days and randomly assigned to one of four light-intensity pedaling groups (15, 30, 45, and 60 min/day). RESULTS: There was 100% adherence in all groups and significant group differences in the minutes pedaled per day (p < .001), with no significant difference in the total pedaling days completed (p = .241). The 15-, 30-, 45-, and 60-min groups experienced a 4.0%, 5.4%, 10.6%, and 11.3% reduction in SB on the days pedaled, respectively. CONCLUSION: Clinically relevant reductions in SB time were achievable in this 1-week trial. Long-term adherence and the impact of replacing SB with seated light activities on geriatric-relevant health outcomes should be investigated.

Isotemporal Substitution of Sedentary Behavior and Physical Activity on Function.

The amount of time spent in sedentary behaviors (SB) progressively increases with age, while reducing time spent in light-intensity physical activity (LPA) and moderate- to vigorous-intensity physical activity (MVPA). These trajectories in PA and SB are linked to accelerated reductions in physical functioning. PURPOSE: This study aimed to examine the association of substituting SB time with LPA and MVPA on physical function in older adults. METHODS: Ninety-one older adults (mean age, 70.7 ± 10.2 yr) wore a hip-mounted accelerometer to measure SB, LPA, and MVPA time. Measures of physical function included a 400-m walk test (400W), the usual gait speed (UGS), the five times sit-to-stand (5xSTS) test, and the short physical performance battery (SPPB). Isotemporal substitution regression modeling was performed to assess the relationship of replacing the amount of time spent in one activity for another. RESULTS: Replacing 30 min·d of SB with LPA was associated with a significant improvement in 400W (P = 0.0497), whereas MVPA resulted in a significant improvement (P < 0.01) in 400W, UGS, 5xSTS, and SPPB. Replacing 60 min·d of SB with 10 min·d of MVPA and 50 min·d of LPA was associated with significant improvements in the 400W, UGS, and 5xSTS (P < 0.05). Meanwhile, as little as 5 min·d of MVPA and 55 min·d of LPA were linked to a 78% increased odds of scoring with good function in the SPPB (P = 0.0247). CONCLUSION: Replacing SB with LPA was linked to a significant improvement in the 400W, but not the other brief functional measures. Mixed doses of LPA and MVPA may add flexibility to interventions targeting reductions of SB in older adults for clinically relevant improvements in physical function.

Acute Passive Static Stretching and Cramp Threshold Frequency.

CONTEXT: Exercise-associated muscle cramps are a common clinical problem for athletes. OBJECTIVE: To determine whether acute passive static stretching altered cramp threshold frequency (CTF) of electrically induced muscle cramps. DESIGN: Crossover study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Seventeen healthy college-aged individuals. INTERVENTION(S): Stretching or no stretching. MAIN OUTCOME MEASURE(S): The independent variable was the static stretch versus the no-stretch condition, and the dependent variable was the CTF. RESULTS: The CTF increased in both the control (pretest: 18.12 ± 6.46 Hz, posttest: 19.65 ± 7.25 Hz; P = .033) and stretching (pretest: 18.94 ± 5.96 Hz, posttest: 20.47 ± 7.12 Hz; P = .049) groups. No difference between the groups was found (t15 = 0.035, P = .97). CONCLUSIONS: Acute passive static stretching did not seem to increase the CTF.

Increasing the Energy Expenditure of Seated Activities in Older Adults with a Portable Elliptical Device.

BACKGROUND: The ill-health effects of sedentary behavior are becoming well-documented, yet older adults spend 70-80% of waking hours sedentary. PURPOSE: To determine if a portable elliptical device increases energy expenditure (EE) while performing popular seated activities. METHODS: Twenty older adults (68.1 ± 1.4 years) participated to compare the measured EE between seated rest and three randomized seated pedaling activities: computer use, reading, TV viewing. Each pedaling activity included 5-min of self-selected paced/no resistance (SSP) and externally paced/added resistance pedaling (Paced). RESULTS: A significant increase in EE existed during SSP (+1.44 ± 0.12 kcal/min) and Paced (+2.19 ± 0.09 kcal/min) pedaling relative to Seated Rest (p < .001). EE during the Paced activities was significantly greater than all SSP activities (p <.01). CONCLUSION: Extrapolating these results, pedaling at a SSP for an hour while performing seated activities is equivalent to the net EE of walking 1.6 miles. Future home-based effectiveness and feasibility should be explored.

Muscle activation and energy expenditure of sedentary behavior alternatives in young and old adults.

The physiological mechanisms that underlie the metabolic benefits of breaking up sedentary behavior (SB) have yet to be determined. The purpose of this study is to compare energy expenditure (EE) and muscle activation (MA) responses to sitting and four SB alternatives in younger and older adults. Twenty-two adults, grouped by age (21-35 and 62-76 years), completed five randomly ordered 20 min tasks: (1) continuous sitting (Sit), (2) sitting on a stability ball (Ball), (3) continuous standing (Stand), (4) sitting interrupted by walking (S/W), and (5) sitting interrupted by standing (S/S). Muscle activation of two upper (trapezius and erector spinae) and two lower (rectus femoris and medial gastrocnemius) body muscles and total body EE were measured continuously. A linear mixed model using gender and age as a covariate with Bonferroni adjustment were used to determine significant differences between tasks. Collectively, S/W produced significantly higher MA and EE compared with Sit (p < 0.001). Stand and Ball provided significantly greater EE, but not MA, compared to Sit (p < 0.05), while S/S did not significantly change EE or MA compared to Sit. There were no net EE differences when comparing age groups across the tasks. Upper body MA was not consistent in both age groups across tasks. Specifically, during S/W the upper body MA of older adults (9.7 ± 1.5% MVC) was double that of young adults (4.8 ± 0.7% MVC, p = 0.006). Lower body MA responded similarly to all tasks in both age groups. Disrupting sitting with walking produced the largest increase in EE and MA compared to other SB alternatives in both age groups. These results are important considering the wide use of SB alternatives by researchers and public health practitioners.