This study determined the load- and limb-dependent neuromuscular responses to fatiguing, bilateral, leg extension exercise performed at a moderate (50% one-repetition maximum [1RM]) and high load (80% 1RM). Twelve subjects completed 1RM testing for the bilateral leg extension, followed by repetitions to failure at 50% and 80% 1RM, on separate days. During all visits, the electromyographic (EMG) and mechanomyographic (MMG), amplitude (AMP) and mean power frequency (MPF) signals were recorded from the vastus lateralis of both limbs. There were no limb-dependent responses for any of the neuromuscular signals and no load-dependent responses for EMG AMP, MMG AMP, or MMG MPF (p = .301–.757), but there were main effects for time that indicated increases in EMG and MMG AMP and decreases in MMG MPF. There was a load-dependent decrease in EMG MPF over time (p = .032) that suggested variability in the mechanism responsible for metabolite accumulation at moderate versus high loads. These findings suggested that common drive from the central nervous system was used to modulate force during bilateral leg extension performed at moderate and high loads.
Taylor K. Dinyer, Pasquale J. Succi, M. Travis Byrd, Caleb C. Voskuil, Evangeline P. Soucie and Haley C. Bergstrom
Nathalie Berninger, Gregory Knell, Kelley Pettee Gabriel, Guy Plasqui, Rik Crutzen and Gill Ten Hoor
Objectives: To examine the bidirectional association of sleep duration with proportions of time spent in physical behaviors among Dutch adolescents. Methods: Adolescents (n = 294, 11–15 years) completed sleep diaries and wore an accelerometer (ActiGraph) over 1 week. With linear mixed-effects models, the authors estimated the association of sleep categories (short, optimal, and long) with the following day’s proportion in physical behaviors. With generalized linear mixed models with binomial distribution, the authors estimated the association of physical behavior proportions on sleep categories. Physical behavior proportions were operationalized using percentages of wearing time and by applying a compositional approach. All analyses were stratified by gender accounting for differing developmental stages. Results: For males (number of observed days: 345, n = 83), short as compared with optimal sleep was associated with the following day’s proportion spent in sedentary (−2.57%, p = .03, 95% confidence interval [CI] [−4.95, −0.19]) and light-intensity activities (1.96%, p = .02, 95% CI [0.27, 3.65]), which was not significant in the compositional approach models. Among females (number of observed days: 427, n = 104), long sleep was associated with the proportions spent in moderate- to vigorous-intensity physical activity (1.69%, p < .001, 95% CI [0.75, 2.64]) and in sedentary behavior (−3.02%, p < .01, 95% CI [−5.09, −0.96]), which was replicated by the compositional approach models. None of the associations between daytime activity and sleep were significant (number of obs.: 844, n = 204). Conclusions: Results indicate partial associations between sleep and the following day’s physical behaviors, and no associations between physical behaviors and the following night’s sleep.
Stephanie L. Silveira, Jessica F. Baird and Robert W. Motl
Three hundred and sixty-three older adults with multiple sclerosis completed a cross-sectional study examining hierarchical correlates of physical activity using a social cognitive theory perspective within a social ecological model (i.e., built environment, social environment, and individual social cognitive theory variables). Hierarchical linear regression analyses were conducted, wherein significant associations were noted for built environment (i.e., land-use mix diversity and aesthetics) and physical activity in Step 1 (R 2 = .09). Social and built environment were significant correlates in Step 2 (R 2 = .15). Finally in Step 3, individual social cognitive theory variables (i.e., self-efficacy and outcome expectations) were the only significant correlates of total physical activity (R 2 = .38). Results were comparable for health-promoting physical activity; however, self-efficacy was the only significant correlate in Step 3 (R 2 = .36). This study provides guidance for researchers and practitioners on relevant targets for tailoring interventions for older adults with multiple sclerosis and supports an emphasis on self-efficacy as a primary predictor of health behavior change.
Junyeon Won, Alfonso J. Alfini, Lauren R. Weiss, James M. Hagberg and J. Carson Smith
Purpose: To examine the effects of a 10-day exercise-training cessation on semantic memory functional activation in older distance runners. Methods: Ten master runners (62.6 ± 7.0 years) with a long-term endurance-training history (29.0 ± 6.0 years) underwent a 10-day training cessation. Before and immediately after the training cessation, semantic memory activation was measured during the famous name recognition task, using functional magnetic resonance imaging. Results: The 10-day training cessation resulted in greater semantic memory activation in three brain regions, including the left inferior frontal gyrus, parahippocampal gyrus, and inferior semilunar lobule. The 10-day training cessation did not significantly alter famous name recognition task performance. Conclusions: The findings demonstrate that even a relatively short period without exercise training alters the functional activation patterns of semantic memory–related neural networks. Increased semantic memory activation after training cessation may indicate reduced neural efficiency during successful memory retrieval.
Alfredo Bravo-Sánchez, Pablo Abián, Filipa Sousa, Fernando Jimenez and Javier Abián-Vicén
Regular sport practice could prevent age-related changes in tendinous tissues. The purpose of the study was to investigate the effect of regular badminton practice on patellar and Achilles tendon mechanical properties in senior competitive badminton players (>35 years old) and to compare the results with physically active people matched by age. One hundred ninety-two badminton players and 193 physically active people were divided by age into four groups, between 35 and 44 (U45), between 45 and 54 (U55), between 55 and 64 (U65), and over 65 (O65) years old. A LogiqS8 transducer in elastography mode and a MyotonPRO myotonometer were used to assess patellar and Achilles mechanical properties. Achilles tendon stiffness was higher in the control group than the badminton players for the U45, U55, and O65 age groups (p < .01). Also, the elastography index was higher in the control group than the badminton players for the U45, U55, U65, and O65 age groups (p < .05). In conclusion, regular badminton practice could prevent the decline in mechanical properties of the patellar and Achilles tendons.
Veronika van der Wardt, Jennie E. Hancox, Clare Burgon, Rupinder Bajwa, Sarah Goldberg and Rowan H. Harwood
Measuring physical activity (PA) in people with mild cognitive impairment or dementia can be difficult. The aim was to investigate the validity and acceptability of three different PA measurement methods. The mixed-method analysis included 49 participants with mild cognitive impairment or dementia, who completed a daily calendar recording PA, the International Physical Activity Questionnaire, and the Longitudinal Aging Study Amsterdam PA Questionnaire, and those who wore a Misfit Shine accelerometer. The quantitative analysis showed equal completion rates for the International Physical Activity Questionnaire and the accelerometer but a lower completion rate for the calendar. Correlations between outcome measures were moderate or strong. The qualitative analysis indicated that all measures were acceptable, though some participants required help to complete the calendars or fasten the accelerometers. The study supported the validity of these methods for people with mild cognitive impairment and mild dementia. Using accelerometers and completing calendars might increase the motivation to be active for some people.
Ryoko Kawakami, Yuko Gando, Kiminori Kato, Susumu S. Sawada, Haruki Momma, Motohiko Miyachi, I-Min Lee, Steven N. Blair, Minoru Tashiro, Chika Horikawa, Yasuhiro Matsubayashi, Takaho Yamada, Kazuya Fujihara and Hirohito Sone
Background: To examine the association between muscular and performance fitness (MPF) and the incidence of glaucoma. Methods: A total of 27,051 glaucoma-free participants aged 20–87 years underwent physical fitness tests between April 2001 and March 2002. The MPF index was calculated using an age- and sex-specific summed z-score from grip strength, vertical jump, single-leg balance, forward bending, and whole-body reaction time. The participants were divided into quartiles according to the MPF index and each physical fitness test. Participants were followed up for the development of glaucoma, which was defined based on physician-diagnosed glaucoma at an annual health examination between April 2002 and March 2008. Hazard ratios for the incidence of glaucoma were estimated using Cox proportional hazards models. Results: During follow-up, 303 participants developed glaucoma. Compared with the lowest MPF index group, hazard ratio (95% confidence interval) of developing glaucoma was 0.64 (0.46–0.89) for the highest MPF index group (P for trend = .001). Vertical jump and whole-body reaction time were associated with incident glaucoma (P for trend = .01 and <.001, respectively). There were no associations between the other physical fitness tests and the incidence of glaucoma. Conclusion: Higher MPF is associated with lower incidence of glaucoma.
Roman P. Kuster, Daniel Baumgartner, Maria Hagströmer and Wilhelmus J.A. Grooten
Background: Sedentary behavior (SB) is associated with several chronic diseases and office workers especially are at increased risk. SB is defined by a sitting or reclined body posture with an energy expenditure of ≤1.5 metabolic equivalents. However, current objective methods to measure SB are not consistent with its definition. There is no consensus on which sensor placement and type should be used. Aim: To compare the accuracy of newly developed artificial intelligence models for 15 sensor placements in combination with four signal types (accelerometer only/plus gyroscope and/or magnetometer) to detect posture and physical in-/activity during desk-based activities. Method: Signal features for the model development were extracted from sensor raw data of 30 office workers performing 10 desk-based tasks, each lasting 5 min. Direct observation (posture) and indirect calorimetry (in-/activity) served as the reference criteria. The best classification model for each sensor was identified and compared among the sensor placements, both using Friedman and post hoc Wilcoxon tests (p ≤ .05). Results: Posture was most accurately measured with a lower body sensor, while in-/activity was most accurately measured with an upper body or waist sensor. The inclusion of additional signal types improved the posture classification for some placements, while the acceleration signal already contained the relevant signal information for the in-/activity classification. Overall, the thigh accelerometer most accurately classified desk-based SB. Conclusion: This study favors, in line with previous work, the measurement of SB with a thigh-worn accelerometer and adds the information that this sensor is also accurate in measuring physical in-/activity while sitting and standing.
Liana M. Tennant, Erika Nelson-Wong, Joshua Kuest, Gabriel Lawrence, Kristen Levesque, David Owens, Jeremy Prisby, Sarah Spivey, Stephanie R. Albin, Kristen Jagger, Jeff M. Barrett, James D. Wong and Jack P. Callaghan
Spinal stiffness and mobility assessments vary between clinical and research settings, potentially hindering the understanding and treatment of low back pain. A total of 71 healthy participants were evaluated using 2 clinical assessments (posteroanterior spring and passive intervertebral motion) and 2 quantitative measures: lumped mechanical stiffness of the lumbar spine and local tissue stiffness (lumbar erector spinae and supraspinous ligament) measured via myotonometry. The authors hypothesized that clinical, mechanical, and local tissue measures would be correlated, that clinical tests would not alter mechanical stiffness, and that males would demonstrate greater lumbar stiffness than females. Clinical, lumped mechanical, and tissue stiffness were not correlated; however, gradings from the posteroanterior spring and passive intervertebral motion tests were positively correlated with each other. Clinical assessments had no effect on lumped mechanical stiffness. The males had greater lumped mechanical and lumbar erector spinae stiffness compared with the females. The lack of correlation between clinical, tissue, and lumped mechanical measures of spinal stiffness indicates that the use of the term “stiffness” by clinicians may require reevaluation; clinicians should be confident that they are not altering mechanical stiffness of the spine through segmental mobility assessments; and greater resting lumbar erector stiffness in males suggests that sex should be considered in the assessment and treatment of the low back.
Behnam Gholami-Borujeni, Ali Yalfani and Leila Ahmadnezhad
This study was conducted to evaluate the effects of 8-week inspiratory muscle training on activity in the ankle muscles of athletes with chronic low-back pain. A randomized controlled trial involving 45 men and women with chronic low-back pain was carried out. Electromyography activity in the tibialis anterior, peroneus longus, gastrocnemius medialis, and gastrocnemius lateralis muscles of the dominant leg was recorded. Secondary outcomes included biopsychosocial indices, such as pain, disability, anxiety and depression, fear-avoidance beliefs, and fear of (re)injury. Static and dynamic overhead squat tests showed that inspiratory muscle training decreased activity in the tibialis anterior, peroneus longus, and gastrocnemius medialis muscles. In the static single-leg squat test and the descending phase of the dynamic equivalent, such a decrease was observed in all the 4 muscles. Inspiratory muscle training significantly reduced pain severity and activity in the tibialis anterior, peroneus longus, and gastrocnemius medialis muscles during the ascending phase of the dynamic single-leg squat test. On the basis of the findings, 8 weeks of inspiratory muscle training may constitute useful rehabilitation for reducing excessive activity in ankle joint muscles and aiding chronic low-back pain recovery.