Purpose: In girls and women, the authors studied the effects of an acute bout of low-impact, moderate-intensity exercise serum on myoblast and osteoblast proliferation in vitro. Methods: A total of 12 pre/early pubertal girls (8–10 y old) and 12 women (20–30 y old) cycled at 60% VO2max for 1 hour followed by 1-hour recovery. Blood samples were collected at rest, mid-exercise, end of exercise, mid-recovery, and end of recovery. C2C12 myoblasts and MC3T3E1 osteoblasts were incubated with serum from each time point for 1 hour, then monitored for 24 hours (myoblasts) or 36 hours (osteoblasts) to examine proliferation. Cells were also monitored for 6 days (myoblasts) to examine myotube formation and 21 days (osteoblasts) to examine mineralization. Results: Exercise did not affect myoblast or osteoblast proliferation. Girls exhibited lower cell proliferation relative to women at end of exercise (osteoblasts, P = .041; myoblasts, P = .029) and mid-recovery (osteoblasts, P = .010). Mineralization was lower at end of recovery relative to rest (P = .014) in both girls and women. Myotube formation was not affected by exercise or group. Conclusion: The systemic environment following one acute bout of low-impact moderate-intensity exercise in girls and women does not elicit osteoblast or myoblast activity in vitro. Differences in myoblast and osteoblast proliferation between girls and women may be influenced by maturation.
Yasmeen Mezil, Joyce Obeid, Inna Ushcatz, Sandeep Raha, and Brian W. Timmons
Marisete P. Safons, Milene S.N. de Lima, Karina F.L. Gonçalves, Gerson A. de Souza Junior, Tito L.C. Barreto, Anderson José S. Oliveira, Alexandre L.A. Ribeiro, Clarissa C. dos Santos Couto Paz, Paulo Gentil, Martim Bottaro, and Wagner R. Martins
The aim of the present study is to compare the effects of 12 weeks of resistance training with machines and elastic tubes on functional capacity and muscular strength in older women aged 60 years or over. The participants were randomized into two groups: a machine group (n = 23) and an elastic group (n = 20). They performed 12 weeks of progressive resistance training, twice a week, with similar exercises. Outcomes were assessed at three time points: baseline, postintervention, and 8 weeks after the end of the training. A significant intragroup effect was demonstrated for both groups at postintervention on functional tests and muscle strength. For the functional reach test and elbow flexion strength (180°/s), only the machine group demonstrated significant intragroup differences. No differences were observed between groups for any outcome. At the 8-week follow-up, functional capacity outcome values were maintained. The muscle strength outcome values decreased to baseline scores, without differences between groups.
Gregore I. Mielke, Inacio Crochemore-Silva, Marlos Rodrigues Domingues, Mariangela Freitas Silveira, Andréa Dâmaso Bertoldi, and Wendy J. Brown
Background: Physical activity levels decrease during pregnancy, and the time course of return to prepregnancy levels is unclear. This study aimed to describe changes in leisure-time physical activity (LTPA) and sitting time from 16 to 24 weeks of pregnancy to 12, 24, and 48 months postpartum in women with different education levels in Brazil. Methods: Data from 4000 mothers of children enrolled in the 2015 Pelotas (Brazil) Birth Cohort were analyzed. The women were interviewed between 16 and 24 weeks of pregnancy and when their children were aged 12, 24, and 48 months. The LTPA and sitting time were self-reported. Results: Only 15.7% of the women reported any LTPA during pregnancy; this declined to 7.9% at 12 months postpartum; it was 16.8% at 24 months and 23.2% at 48 months. On average, participants spent a mean (SD) of 6.4 (3.9), 4.2 (3.2), 4.3 (3.3), and 4.4 (3.3) hours per day sitting during pregnancy, and at 12, 24, and 48 months after the birth, respectively. Both any LTPA and high sitting (8+ h/d) were consistently higher among women with higher education. Conclusion: After 24 months postpartum, LTPA levels had returned to or exceeded pregnancy levels, but sitting time remained lower than during pregnancy.
Ashley Kuzmik, Barbara Resnick, Pamela Cacchione, Rachel Arendacs, and Marie Boltz
Persons with dementia are at high risk for hospital-acquired disability, associated with low physical activity during hospitalizations. To determine the effectiveness of efforts to increase physical activity, a valid and reliable measurement approach is required. Data from an ongoing cluster randomized clinical trial examined the feasibility and validity of the MotionWatch 8 (MW8) triaxial actigraphy device. The sample included 321 participants of which 259 (81%) were willing to wear the MW8 for 24 hr. Regression analysis revealed that time in low activity, β = 0.17, t(255) = 2.9, p = .004, and time in moderate activity, β = 0.14, t(255) = 2.4, p = .017, measured by the MW8, were associated with participants’ physical function. Engagement in moderate physical activity was associated with return to baseline function at discharge (Wald χ2 = 4.10, df = 1, p = .043). The study provides preliminary support for the feasibility and validity of the MW8 in hospitalized persons with dementia.
Cézane Priscila Reuter, Caroline Brand, João Francisco de Castro Silveira, Letícia de Borba Schneiders, Jane Dagmar Pollo Renner, Letícia Borfe, and Ryan Donald Burns
Purpose: To verify the reciprocal longitudinal relationships between cardiorespiratory fitness (CRF), percentage body fat (%body fat), and metabolic syndrome in Brazilian primary school students. Method: This longitudinal study involved 420 children and adolescents followed for 3 years (2011–2014). The continuous Metabolic Syndrome (cMetSyn) score was calculated by summing adjusted z scores of glucose, systolic blood pressure, total cholesterol/high-density lipoprotein cholesterol ratio, triglycerides, and waist circumference. The CRF was assessed using running/walking tests, and %body fat was assessed through sex-specific 2-site skinfold thickness. Cross-lagged panel models were used to analyze longitudinal reciprocal relationships between CRF and %body fat with cMetSyn. Results: Results indicated that 2011 %body fat significantly predicted both 2014 CRF scores and 2014 cMetSyn scores (P < .001); however, 2011 CRF only predicted 2014 %body fat (P < .001) but not 2014 cMetSyn (P = .103). Furthermore, 2011 cMetSyn predicted 2014 %body fat (P = .002). The model explained 36%, 48%, and 37% of the variance in 2014 CRF, %body fat, and cMetSyn, respectively. Conclusion: The results suggest a reciprocal inverse relationship between %body fat and metabolic syndrome risk and that %body fat may play a more important role in the risk of developing metabolic syndrome compared with CRF.
Christopher R.J. Fennell and James G. Hopker
Purpose: There has been paucity in research investigating the individualization of recovery interval duration during cycling-based high-intensity interval training (HIIT). The main aim of the study was to investigate whether individualizing the duration of the recovery interval based upon the resolution of muscle oxygen consumption would improve the performance during work intervals and the acute physiological response of the HIIT session, when compared with a standardized (2:1 work recovery ratio) approach. Methods: A total of 16 well-trained cyclists (maximal oxygen consumption: 60  mL·kg−1·min−1) completed 6 laboratory visits: (Visit 1) incremental exercise test, (Visit 2) determination of the individualized (IND) recovery duration, using the individuals’ muscle oxygen consumption recovery duration to baseline from a 4- and 8-minute work interval, (Visits 3–6) participants completed a 6 × 4- and a 3 × 8-minute HIIT session twice, using the IND and standardized recovery intervals. Results: Recovery duration had no effect on the percentage of the work intervals spent at >90% and >95% of maximal oxygen consumption, maximal minute power output, and maximal heart rate, during the 6 × 4- and 3 × 8-minute HIIT sessions. Recovery duration had no effect on mean work interval power output, heart rate, oxygen consumption, blood lactate, and rating of perceived exertion. There were no differences in reported session RPE between recovery durations for the 6 × 4- and 3 × 8-minute HIIT sessions. Conclusion: Individualizing HIIT recovery duration based upon the resolution of muscle oxygen consumption to baseline levels does not improve the performance of the work intervals or the acute physiological response of the HIIT session, when compared with standardized recovery duration.
Bernhard Prinz, Dieter Simon, Harald Tschan, and Alfred Nimmerichter
Purpose: To determine aerobic and anaerobic demands of mountain bike cross-country racing. Methods: Twelve elite cyclists (7 males;
Jennifer R. Pharr, Jason D. Flatt, Lung-Chang Chien, Axenya Kachen, and Babayemi O. Olakunde
Introduction: There is a positive association between exercise and improved mental health in the general population. Although there is a greater burden of psychological distress among lesbian, gay, and bisexual (LGB) people, little is known about the association between exercise and mental health in this population. The authors explored the association between exercise and poor mental health reported by LGB adults in the United States. Methods: Our analyses used data from the 2017 Behavioral Risk Factor Surveillance System survey. Multiple regression analyses were used to determine the association between exercising and mental health days adjusting for sociodemographic characteristics. Results: Data were available for 6371 LGB participants. LGB adults who participated in any exercise reported almost 1.0 day less of poor mental health in the past 30 days compared with LGB adults who did not exercise (P ≤ .01). LGB adults who met one or both of the physical activity guidelines had between 1.2 and 1.7 days less of poor mental health compared with those who did not meet the guidelines (P ≤ .01). Conclusion: Fewer days of poor mental health were reported by LGB adults who exercised. Determining whether physical activity interventions, including aerobic and strengthening exercises, could improve mental health outcomes in LGB adults should be studied.
Sebastian Kaufmann, Ralph Beneke, Richard Latzel, Hanna Pfister, and Olaf Hoos
Purpose: To elucidate the role of inter-effort recovery in shuttle running by comparing the metabolic profiles of the 30-15 Intermittent Fitness Test (30-15IFT) and the corresponding continuous version (30-15IFT-CONT). Methods: Sixteen state-level handball players (age = 23  y, height = 185  cm, weight = 85  kg) completed the 30-15IFT and 30-15IFT-CONT, and speed at the last completed stage (in kilometers per hour) and time to exhaustion (in seconds) were assessed. Furthermore, oxygen uptake (in milliliters per kilogram per minute) and blood lactate were obtained preexercise, during exercise, and until 15 minutes postexercise. Metabolic energy (in kilojoules), metabolic power (in Watts per kilogram), and relative (in percentage) energy contribution of the aerobic (WAER, WAERint), anaerobic lactic (WBLC, WBLCint), and anaerobic alactic (WPCr, WPCrint) systems were calculated by PCr-La-O2 method for 30-15IFT-CONT and 30-15IFT. Results: No difference in peak oxygen uptake was found between 30-15IFT and 30-15IFT-CONT (60.6 [6.6] vs 60.5 [5.1] mL·kg−1·min−1, P = .165, d = 0.20), whereas speed at the last completed stage was higher in 30-15IFT (18.3 [1.4] vs 16.1 [1.0] km·h−1, P < .001, d = 1.17). Metabolic energy was also higher in 30-15IFT (1224.2 [269.6] vs 772.8 [63.1] kJ, P < .001, d = 5.60), and metabolic profiles differed substantially for aerobic (30-15IFT = 67.2 [5.2] vs 30-15IFT-CONT = 85.2% [2.5%], P < .001, d = −4.01), anaerobic lactic (30-15IFT = 4.4 [1.4] vs 30-15IFT-CONT = 6.2% [1.8%], P < .001, d = −1.04), and anaerobic alactic (30-15IFT = 28.4 [4.7] vs 30-15IFT-CONT = 8.6% [2.1%], P < .001, d = 5.43) components. Conclusions: Both 30-15IFT and 30-15IFT-CONT are mainly fueled by aerobic energy, but their metabolic profiles differ substantially in both aerobic and anaerobic alactic energy contribution. Due to the presence of inter-effort recovery, intermittent shuttle runs rely to a higher extent on anaerobic alactic energy and a fast, aerobic replenishment of PCr during the short breaks between shuttles.
Subir Gupta, Arkadiusz Stanula, and Asis Goswami
Purpose: To determine (1) the time of arrival of peak blood lactate concentration ([BLa]peak) followed by various track events and (2) significant correlation, if any, between average velocity and [BLa]peak in these events. Methods: In 58 under-20 male track athletes, heart rate was recorded continuously and blood lactate concentration was determined at various intervals following 100-m (n = 9), 200-m (n = 8), 400-m (flat) (n = 9), 400-m hurdles (n = 8), 800-m (n = 9), 1500-m (n = 8), 3000-m steeplechase (n = 7), and 5000-m (n = 10) runs. Results: The [BLa]peak, in mmol/L, was recorded highest following the 400-m run (18.27 [3.65]) followed by 400-m hurdles (16.25 [3.14]), 800-m (15.53 [3.25]), 1500-m (14.71 [3.00]), 200-m (14.42 [3.40]), 3000-m steeplechase (11.87 [1.48]), 100-m (11.05 [2.36]), and 5000-m runs (8.65 [1.60]). The average velocity of only the 400-m run was found to be significantly correlated (r = .877, p < 0.05) with [BLa]peak. The arrival time of [BLa]peak following 100-m, 200-m, 400-m, 400-m hurdles, 800-m, 1500-m, 3000-m steeplechase, and 5000-m runs was 4.44 (0.83), 4.13 (0.93), 4.22 (0.63), 3.75 (0.83), 3.34 (1.20), 2.06 (1.21), 1.71 (1.44), and 1.06 (1.04) minutes, respectively, of the recovery period. Conclusion: In under-20 runners, (1) [BLa]peak is highest after the 400-m run, (2) the time of appearance of [BLa]peak varies from one event to another but arrives later after sprint events than longer distances, and (3) the 400-m (flat) run is the only event wherein the performance is significantly correlated with the [BLa]peak.