Context: Several studies report static-stretch-induced deficits and dynamic-stretch performance improvement after intervention. Purpose: To investigate the muscle activation of the forehand and backhand in table tennis players after experiencing static- and dynamic-stretching protocols. Methods: A total of 24 elite male table tennis players (age 22.7 [3.46] y, height 1.78 [0.03] m) were tested before and 0, 10, 20, and 30 min after the 3 conditions (dynamic stretch, static stretch, and no stretch). The MEGA ME6000 (Mega Electronics, Kuopio, Finland) was used to capture the surface EMG data of the anterior deltoid, middle deltoid, posterior deltoid, biceps, and triceps muscles. Muscle activation data of the pretest were compared with posttest 0, 10, 20, and 30 min. These data were also compared between 3 different conditions (dynamic stretch, static stretch, and no stretch). Results: A 2-way repeated-measures analysis of variance indicated significant differences in the forehand and backhand, and Bonferroni test as a post hoc comparison revealed significant differences between the pretest and posttests in several muscles (P < .05). Furthermore, there were significant differences in the posttest between the 3 conditions (P < .05). Conclusions: In general, there was a short-term effect of static- and dynamic-stretching protocols on glenohumeral-joint muscle activation in elite table tennis players. The static and dynamic stretching presented a decrease and increase, respectively, in muscle activation up to 30 min after stretching. In conclusion, the additive and subtractive effects of dynamic- and static-stretching protocols on muscle activation seem to persist after 30 min.
Omid Kazemi, Amir Letafatkar and Paulo H. Marchetti
Justin J. Merrigan, James J. Tufano, Michael Falzone and Margaret T. Jones
Purpose: To identify acute effects of a single accentuated eccentric loading (AEL) repetition on subsequent back-squat kinetics and kinematics with different concentric loads. Methods: Resistance-trained men (N = 21) participated in a counterbalanced crossover design and completed 4 protocols (sets × repetitions at eccentric/concentric) as follows: AEL65, 3 × 5 at 120%/65% 1-repetition maximum (1-RM); AEL80, 3 × 3 at 120%/80% 1-RM; TRA65, 3 × 5 at 65%/65% 1-RM; and TRA80, 3 × 3 at 80%/80% 1-RM. During AEL, weight releasers disengaged from the barbell after the eccentric phase of the first repetition and remained off for the remaining repetitions. All repetitions were performed on a force plate with linear position transducers attached to the barbell, from which eccentric and concentric peak and mean velocity, force, and power were derived. Results: Eccentric peak velocity (−0.076 [0.124] m·s−1; P = .01), concentric peak force (187.8 [284.4] N; P = .01), eccentric mean power (−145.2 [62.0] W; P = .03), and eccentric peak power (−328.6 [93.7] W; P < .01) during AEL65 were significantly greater than TRA65. When collapsed across repetitions, AEL65 resulted in slower eccentric velocity and power during repetition 1 but faster eccentric and concentric velocity and power in subsequent repetitions (P ≤ .04). When comparing AEL80 with TRA80, concentric peak force (133.8 [56.9] N; P = .03), eccentric mean power (−83.57 [38.0] W; P = .04), and eccentric peak power (−242.84 [67.3] W; P < .01) were enhanced. Conclusions: Including a single supramaximal eccentric phase of 120% 1-RM increased subsequent velocity and power with concentric loads of 65% 1-RM, but not 80% 1-RM. Therefore, AEL is sensitive to the magnitude of concentric loads, which requires a large relative difference to the eccentric load, and weight releasers may not need to be reloaded to induce performance enhancement.
Joel L. Prowting, Debra Bemben, Christopher D. Black, Eric A. Day and Jason A. Campbell
The authors sought to determine whether consuming collagen peptides (CP) enhances musculoskeletal recovery of connective tissues following a damaging exercise bout. Resistance-trained males consumed 15 g/day of CP (n = 7) or placebo (n = 8), and after 7 days, maximal voluntary isometric contraction (MVIC), countermovement jump height, soreness, and collagen turnover were examined. Five sets of 20 drop jumps were performed and outcome measures were collected 24, 48, and 120 hr postexercise. Countermovement jump height was maintained in the CP group at 24 hr (PRE = 39.9 ± 8.8 cm vs. 24 hr = 37.9 ± 8.9 cm, p = .102), whereas the CP group experienced a significant decline at 24 hr (PRE = 40.4 ± 7.9 cm vs. 24 hr = 35.5 ± 6.4 cm, p = .001; d = 0.32). In both groups, muscle soreness was significantly higher than PRE at 24 hr (p = .001) and 48 hr (p = .018) but not at 120 hr (p > .05). MVIC in both legs showed a significant time effect (left: p = .007; right: p = .010) over the 5-day postexercise period. Neither collagen biomarker changed significantly at any time point. CP supplementation attenuated performance decline 24 hr following muscle damage. Acute consumption of CP may provide a performance benefit the day following a bout of damaging exercise in resistance-trained males.
Stefano Montanari, Mehmet A. S¸ahin, Ben J. Lee, Sam D. Blacker and Mark E.T. Willems
Supplementation with anthocyanin-rich blackcurrant increases blood flow, cardiac output, and stroke volume at rest. It is not known whether cardiovascular responses can be replicated over longer timeframes in fed trained cyclists. In a randomized, double-blind, crossover design, 13 male trained cyclists (age 39 ± 10 years,
Ava Farley, Gary J. Slater and Karen Hind
Athletic populations require high-precision body composition assessments to identify true change. Least significant change determines technical error via same-day consecutive tests but does not integrate biological variation, which is more relevant for longitudinal monitoring. The aim of this study was to assess biological variation using least significant change measures from body composition methods used on athletes, including surface anthropometry (SA), air displacement plethysmography (BOD POD), dual-energy X-ray absorptiometry (DXA), and bioelectrical impedance spectroscopy (BIS). Thirty-two athletic males (age = 31 ± 7 years; stature = 183 ± 7 cm; mass = 92 ± 10 kg) underwent three testing sessions over 2 days using four methods. Least significant change values were calculated from differences in Day 1 Test 1 versus Day 1 Test 2 (same-day precision), as well as Day 1 Test 1 versus Day 2 (consecutive-day precision). There was high agreement between same-day and consecutive-day fat mass and fat-free mass measurements for all methods. Consecutive-day precision error in comparison with the same-day precision error was 50% higher for fat mass estimates from BIS (3,607 vs. 2,331 g), 25% higher from BOD POD (1,943 vs. 1,448 g) and DXA (1,615 vs. 1,204 g), but negligible from SA (442 vs. 586 g). Consecutive-day precision error for fat-free mass was 50% higher from BIS (3,966 vs. 2,276 g) and SA (1,159 vs. 568 g) and 25% higher from BOD POD (1,894 vs. 1,450 g) and DXA (1,967 vs. 1,461 g) than the same-day precision error. Precision error in consecutive-day analysis considers both technical error and biological variation, enhancing the identification of small, yet significant changes in body composition of resistance-trained male athletes. Given that change in physique is likely to be small in this population, the use of DXA, BOD POD, or SA is recommended.
Irina Burchard Erdvik, Tommy Haugen, Andreas Ivarsson and Reidar Säfvenbom
This study investigated the temporal relations of adolescents’ basic need satisfaction in physical education (PE) and global self-worth in a sample of 3,398 lower and upper secondary school students (49% boys, 51% girls, average age T1 = 15.00, SD = 1.79). Four models and competing hypotheses were tested, and the model with bidirectional paths specified showed the best fit to the data. The bidirectional effect estimates suggest not only that basic need satisfaction in PE predicts global self-worth development but also that adolescents’ perceptions of global self-worth predict the degree to which they experience basic need satisfaction in PE. Findings could suggest that students with low global self-worth are less sensitive to basic need support in PE. These students may need personally tailored need-supportive initiatives in order to develop basic need satisfaction in PE and, thus, global self-worth through PE.
Daichi Tomita, Tadashi Suga, Hiromasa Ueno, Yuto Miyake, Takahiro Tanaka, Masafumi Terada, Mitsuo Otsuka, Akinori Nagano and Tadao Isaka
This study examined the relationship between Achilles tendon (AT) length and 100-m sprint time in sprinters. The AT lengths at 3 different portions of the triceps surae muscle in 48 well-trained sprinters were measured using magnetic resonance imaging. The 3 AT lengths were calculated as the distance from the calcaneal tuberosity to the muscle–tendon junction of the soleus, gastrocnemius medialis, and gastrocnemius lateralis, respectively. The absolute 3 AT lengths did not correlate significantly with personal best 100-m sprint time (r = −.023 to .064, all Ps > .05). Furthermore, to minimize the differences in the leg length among participants, the 3 AT lengths were normalized to the shank length, and the relative 3 AT lengths did not correlate significantly with personal best 100-m sprint time (r = .023 to .102, all Ps > .05). Additionally, no significant correlations were observed between the absolute and relative (normalized to body mass) cross-sectional areas of the AT and personal best 100-m sprint time (r = .012 and .084, respectively, both Ps > .05). These findings suggest that the AT morphological variables, including the length, may not be related to superior 100-m sprint time in sprinters.
Madison C. Chandler, Amanda L. McGowan, Ford Burles, Kyle E. Mathewson, Claire J. Scavuzzo and Matthew B. Pontifex
While compelling evidence indicates that poorer aerobic fitness relates to impairments in retrieving information from hippocampal-dependent memory, there is a paucity of research on how aerobic fitness relates to the acquisition of such relational information. Accordingly, the present investigation examined the association between aerobic fitness and the rate of encoding spatial relational memory—assessed using a maximal oxygen consumption test and a spatial configuration task—in a sample of 152 college-aged adults. The findings from this investigation revealed no association between aerobic fitness and the acquisition of spatial relational memory. These findings have implications for how aerobic fitness is characterized with regard to memory, such that aerobic fitness does not appear to relate to the rate of learning spatial–relational information; however, given previously reported evidence, aerobic fitness may be associated with a greater ability to recall relational information from memory.
Jihyun Lee, Seung Ho Chang and Jerred Jolin
The motor and social skill difficulties experienced by many children with autism spectrum disorder (ASD) can create challenges when participating in age appropriate physical activity contexts. Although behavioral interventions can increase the general social communicative skills of children with ASD, often the skills targeted are not relevant to physical activity contexts. Thus, this pilot study utilized a movement-based intervention program to support children with ASD in learning both social and movement skills that are relevant to physical activity contexts. Nineteen children with ASD with a mean age of 9.3 (±3.0) years participated in this program for 8 weeks, twice a week, at a recreation center as an afterschool activity. Six object control skills were selected and tested before and after the intervention because these gross motor skills were considered to elicit human interactions and place demands on social skills. Ten social skills were selected, aligned to each program context, taught, and evaluated. This intervention resulted in significant improvements in object-control skills for the participants. Additionally, there were significantly more participants who demonstrated improvements in their performance of the target social skills than who did not demonstrate improvements. These preliminary findings provide support for the feasibility of developing interventions that address social skill deficits in the context of physically active settings for children with ASD.
Aliaa M. Elabd, Salah-Eldin B. Rasslan, Haytham M Elhafez, Omar M. Elabd, Mohamed A. Behiry and Ahmed I. Elerian
Although current lumbar stabilization exercises are beneficial for chronic mechanical low back pain, further research is recommended focusing on global spinal alignment normalization. This randomized, controlled, blinded trial was conducted to determine the effects of adding cervical posture correction to lumber stabilization on chronic mechanical low back pain. Fifty adult patients (24 males) with chronic mechanical low back pain and forward head posture received 12 weeks treatment of either both programs (group A) or lumbar stabilization (group B). The primary outcome was back pain. The secondary outcomes included the craniovertebral angle, Oswestry Disability Index, C7-S1 sagittal vertical axis, and sagittal intervertebral movements. The multivariate analysis of variance indicated a significant group-by-time interaction (P = .001, partial η 2 = .609). Pain, disability, C7-S1 sagittal vertical axis, and l2-l3 intervertebral rotation were reduced in group A more than B (P = .008, .001, .025, and .001). Craniovertebral angle was increased in A when compared to B (P = .001). However, there were no significant group-by-time interactions for other intervertebral movements. Within-group comparisons were significant for all outcomes except for craniovertebral angle within patients in the control group. Adding cervical posture correction with lumber stabilization for management of chronic low back pain seemed to have better effects than the application of a stabilization program only.