A 5-Week Guided Active Play Program Modulates Skin Microvascular Reactivity in Healthy Children.

PURPOSE: Children's poor levels of physical activity (PA) participation and early-onset vascular aging are identified as global health challenges. Children's guided activity play (GAP)-based PA programs have emerged as effective strategies to improve cardiovascular risk factors and health-related fitness. This study proposes to investigate whether GAP improves children's cutaneous microvascular reactivity and health-related fitness. METHODS: Children's (n = 18; 9.8 [1.5] y) PA during a 5-week (4 d/wk; 1 h/d) GAP program was assessed (accelerometry) with preassessments and postassessments for anthropometric, musculoskeletal fitness, blood pressure, estimated aerobic power, and cutaneous microvascular reactivity. RESULTS: PA averaged 556 (132) kcal·week-1 at 34.7% (7.5%) time at moderate to vigorous intensity. Resting heart rate (-9.5%) and diastolic blood pressure (-7.8%) were reduced without changes in health-related fitness indices. Cutaneous microvascular reactivity to sodium nitroprusside iontophoresis increased the average perfusion (+36.8%), average cutaneous vascular conductance (+30%), the area under the curve (+28.8%), and a faster rise phase (+40%) of perfusion (quadratic modeling; P ≤ .05). Chi-square and crosstabulation analysis revealed significant association between children's PA levels and sodium nitroprusside average perfusion levels, where children with PA levels ≥205.1 kcal.55 minute-1 were overrepresented in the medium/high levels of sodium nitroprusside perfusion. CONCLUSION: A 5-week GAP modified the microvascular reactivity in children without changes in body mass, musculoskeletal fitness, or estimated aerobic power.

Scientific meeting report: International Biochemistry of Exercise 2022.

Exercise is one of the only nonpharmacological remedies known to counteract genetic and chronic diseases by enhancing health and improving life span. Although the many benefits of regular physical activity have been recognized for some time, the intricate and complex signaling systems triggered at the onset of exercise have only recently begun to be uncovered. Exercising muscles initiate a coordinated, multisystemic, metabolic rewiring, which is communicated to distant organs by various molecular mediators. The field of exercise research has been expanding beyond the musculoskeletal system, with interest from industry to provide realistic models and exercise mimetics that evoke a whole body rejuvenation response. The 18th International Biochemistry of Exercise conference took place in Toronto, Canada, from May 25 to May 28, 2022, with more than 400 attendees. Here, we provide an overview of the most cutting-edge exercise-related research presented by 66 speakers, focusing on new developments in topics ranging from molecular and cellular mechanisms of exercise adaptations to exercise therapy and management of disease and aging. We also describe how the manipulation of these signaling pathways can uncover therapeutic avenues for improving human health and quality of life.

Guided Active Play Promotes Physical Activity and Improves Fundamental Motor Skills for School-Aged Children.

Reports show that children's physical activity (PA) levels are related to FMS proficiency; however, whether PA levels directly improve FMS is uncertain. This study investigated the responses of PA levels and FMS proficiency to active play (AP) and guided active play (GAP) interventions. Three community programs (seven-weeks; 4d·wk-1) were randomly assigned to: i) active play (CON); ii) locomotor skills (LOC) guided active play (GAP); and iii) object control skills (OC) GAP groups. Children's (n = 52; 6.5 (0.9) yr) interventions included continuous and/or intermittent cooperative games focused on either locomotor skills (i.e. blob tag, red-light-green-light) or object control skills i.e., hot potato, racket balloons, 4-way soccer). PA levels (accelerometers) were assessed on 2 of 4 sessions per week throughout the program. The Test of Gross Motor Development-2 (TGMD-2) was used to assess FMS scores. The changes for CON and LOC interventions for locomotor standard scores were -0.83 (2.61) vs. 2.6 (2.64) (α = 0.022), for locomotor percentiles -9.08 (36.7) vs. 20.1 (30.4) (α = 0.033) and for gross motor quotient percentiles -4.3 (30.3) vs. 24.1 (29.6) (α = 0.022). Children's PA levels averaged 158.6 (6.6) kcal·55min-1 for CON vs. 174.5 (28.3) kcal.55min-1 for LOC (α = 0.089) and 170.0 (20.1) kcal·55min-1 for OC (α = 0.144). Moderate-Vigorous PA was 18.4 (8.0) %, 47.9 (7.8) % (α = 0.000) and 51.9 (6.0) % (α = 0.000) for CON, LOC and OC, while time at sedentary/very light PA was 36.4 (9.8) %, 15.1 (4.9) % (α = 0.000) and 14.9 (15.9) %Sed/VL (α = 0.001) during the 7-week program. The OC intervention showed more upper body movement experiences compared to the LOC program (p = 0.020). A guided active play program using LOC cooperative games showed increases in energy expenditure and %MVPA and improved FMS proficiency, but active play did not. For school-aged children (5-7 yr) guided active play using cooperative games may be an effective strategy to improve FMS and promote health and fitness benefits.

Characteristics of children's physical activity during active play.

BACKGROUND: Emerging evidence suggests that oxygen consumption (VO2) for self-paced physical activity (PA) is underestimated when applying laboratory-based treadmill (TM)-derived regression equations. This study examines the accelerometer (ACC) characteristics for paced TM PA and self-paced children's PA to ascertain if the predictable regulated patterns of paced PA are implicated in the inferior estimates of VO2. METHODS: Children's (9.3±1.2 years) (N.=21) VO2 (portable oxygen analyzer) and PA (accelerometry) were measured for paced treadmill PA (4-10 km/h). Active playing of children's games in a camp setting was used for self-paced PA. Treadmill and self-paced PA were compared by linear regression and Bland-Altman analysis. Relative contribution of each axes (% axis difference) for paced and self-paced PA were assessed (N.=21). RESULTS: The VO2 responses during paced treadmill exercise was linear with ACC quantified PA (for vertical axis r=0.95±0.03 and for vector magnitude [VM] r=0.95±0.05, P>0.05). During self-paced PA, the VO2 responses for ACC quantified PA were not linear (for vertical axis r=0.20±0.11 and for VM r=0.25±0.09) over the same range of ACC PA (0-1500 counts/10 s). VO2 estimates for self-paced PA (using TM-derived equations) were underestimated (P<0.05) across the range of intensities, which increased as the intensity of PA increased (>6 METs). Comparing paced versus self-paced PA the % axis dominance (i.e., difference between the highest and lowest axis) contribution to PA was 41±14% for paced and 3±2% for self-paced PA (P<0.05). CONCLUSIONS: This study reveals that the inferior estimates of VO2 for self-paced PA (using-derived linear equations) is attributable to the presence of a dominant axis with paced TM PA, which inflates the calculation of VM and the predicted VO2 for self-paced PA where no % axis difference exists.

Children and adolescent physical activity participation and enjoyment during active play.

BACKGROUND: Girls' (9-19 years) participation in physical activity (PA) is known to decrease at a faster rate than boys. A reduction in PA attractiveness (enjoyment) and lower psychosocial profile of girls approaching biological maturity may underlie the decreasing rate of PA participation. Since engaging children in active play programs improves health related quality of life indictors and enjoyment levels; the purposes of this study were to: 1) assess psychosocial status and PA attractiveness/enjoyment of boys and girls to an eight-week active play program; and 2) investigate the relationships among PA participation, psychosocial status and PA attractiveness with both age and maturity status for boys and girls following an active play PA program. METHODS: Thirty-three children (age 9.8±1.3 years; weight 43.1±13.4 kg; BMI 20.8±3.2 kg/m2) were recruited to participate in an active play program for 8 weeks (4x/week; 1hr/d). M-S estimates ranged from -6.7 to -2.5 years away from biological maturity Daily program PA was assessed and compared to pre-post measures of psychosocial functioning and PA attractiveness. Statistical procedures were performed using ANOVA and/or Pearson's correlation r (SPSS v. 22.0) with P=0.05. RESULTS: PA participation in the active play program showed a group average of 39±11% time spent in moderate-vigorous PA (%MVPA) with boys averaging 45% MVPA and girls averaging 30% MVPA (P<0.05). PA attractiveness scores for boys did not change following the program; whereas girls improved from 67±13% to 76±9% (P<0.05). Minimal changes were noted for the health-related quality of life measures as a result of the PA program. Comparing PA attractiveness to %MVPA, 80% of girls reporting positive changes or no change; in contrast 56% of boys responded with negative/less PA attractiveness. PA attractiveness for all children was negatively associated with age (r=-0.19) and/or M-S (r=-0.29). The relationships, however, were gender specific with boys exhibiting a coefficient of -0.28 (age) and -0.61 (M-S) (P<0.05). For girls, increased PA attractiveness promoted less decline in %MVPA for M-S (r=0.18) compared to age (r=-0.17). CONCLUSIONS: For girls, approaching biological maturity, PA enjoyment/attractiveness can be positively influenced with an active play program, which is a major consideration promoting PA participation in girls but not boys.

Cardiorespiratory and metabolic responses associated with children's physical activity during self-paced games.

The aim of this study was to explore the possibility of identifying clusters of children's games based on estimated energy expenditures and (or) intensity when performed in a guided active play format. The study also investigated whether the identified active play game clusters were repeatable when the games were performed on different days. Children (9.7 ± 1.1 years; n = 12) were assessed for oxygen consumption, heart rate, energy expenditure (EE), and metabolic equivalent (MET) on a treadmill (at 4, 6, and 8 km·h(-1) (0% grade)). HR and ActiGraph GT1M accelerometer (ACC) generated linear regression equations were used to estimate EE. The ACC (3 s epochs) were used for estimating METs in assigning percent time at medium-vigorous physical activity (%MVPA) of 10 self-paced games. The results showed a consistent range of EEs (ACC-equation) from 13.57 kcal·(5 min)(-1) to 25.00 kcal·(5 min)(-1) (p < 0.05); EEs (HR-equation) from 29.72 to 42.49 kcal·(5 min)(-1) (p < 0.05); and %MVPA from 10% to 34% (p < 0.05) (from ACC equations) across all games. These were reproducible from day to day (p > 0.05). This study confirms the existence of active play children's game clusters that might be useful in formatting guided active play in a dose-response manner for children.

Calpain/calpastatin activities and substrate depletion patterns during hindlimb unweighting and reweighting in skeletal muscle.

Unloading of skeletal muscle by hindlimb unweighting (HU) is characterized by atrophy, protein loss, and an elevation in intracellular Ca(2+) levels that may be sufficient to activate Ca(2+)-dependent proteases (calpains). In this study, we investigated the time course of calpain activation and the depletion pattern of a specific structural protein (desmin) with unloading and subsequent reweighting. Rats underwent 12 h, 24 h, 72 h or 9 days of HU, followed by reweighting for either 0, 12 or 24 h. Total calpain-like activity was elevated with HU in skeletal muscle (P < 0.05) and was further enhanced with reweighting (P < 0.05). The increases in calpain-like activity were associated with a proportional increase in activity of the particulate fraction (P < 0.05). Activity of the mu-calpain isoform was elevated with 12 and 24 h of HU (P < 0.05) and returned to control levels thereafter. With reweighting, activities of mu-calpain were elevated above control levels for all HU groups except 9 days (P < 0.05). In contrast, minimal changes in m-calpain and calpastatin activity were observed with HU and reweighting. Although desmin depletion levels did not reach statistical significance, a significant inverse relationship was found between the mu-calpain/calpastatin ratio and the amount of desmin in isolated myofibrils (R = -0.83, P < 0.001). The results suggest that calpain activation is an early event during unloading in skeletal muscle, and that the majority of the increase in calpain activity can be attributed to the micro-isoform.

Early activation and redistribution of calpain activity in skeletal muscle during hindlimb unweighting and reweighting.

The aims of this study were the following: (i) to determine whether activation of the Ca2+-activated protease, calpain, is an early event during hindlimb unweighting (HU) in skeletal muscle; and (ii) to assess whether calpain activity is greater during reweighting compared with HU alone. Rats were exposed to 12, 24, and 72 h, or 9 d of HU, followed by reweighting for 0, 12, or 24 h. Calpain activities were assayed for total, soluble, and particulate fractions. Total calpain activity was increased in the soleus at all HU time points, whereas activities were elevated in the gastrocnemius only after 9 d of HU. With reweighting, calpain activity remained elevated at all time points for both muscles. In general, reweighting the gastrocnemius increased its calpain activity more than during HU only, whereas reweighting the soleus did not produce additional increases in its calpain activity. The increases in calpain activity were associated with a proportional increase in activity of the particulate (membrane- and protein-associated) fraction. The results suggest that calpain activation is an early event during HU in the soleus, and that the increases in calpain activity in both muscles are associated with a redistribution of activity from cytosolic to particulate fractions.