The Effects of an Inclusive Badminton Program on Static Postural Control for Individuals with Intellectual and Developmental Disabilities.

The purpose of the study was to examine static postural control/balance in young adults with intellectual and developmental disabilities (IDD) and typically developing (TD) young adults before, during, and after an inclusive badminton intervention. Eight participants (four IDD-BADM and four TD-BADM) participated in a 12-week inclusive badminton intervention, with the other eight participants as matched controls (four IDD-CONTR and four TD-CONTR) (74.19 kg ± 9.8 kg, 171.96 cm ± 5.4 cm; 21.7 ± 1.8 years of age; nine females and seven males; eight with IDD and eight TD). The study followed a repeated measures design (pre, mid, post) before the intervention, at 6 weeks, and after 12 weeks. Static postural sway conditions included: bilateral stance eyes open (20 s), eyes closed (10 s), foam eyes open (20 s), foam eyes closed (10 s), and unilateral stance eyes open (10 s) and foam eyes open (10 s). Sway measurements included: average anterior/posterior (A/P) displacement (in), average medial/lateral (M/L) displacement (in), average 95% ellipsoid area (in2), and average velocity (ft/s). Significant time × group interactions were reported for average velocity (EO) (p = 0.030), average length (EO) (p = 0.030), 95% ellipsoid area (EO) (p = 0.049), and average A/P displacement (1LEO) (p = 0.036) for IDD-BADM. Significant time main effects were reported for average A/P displacement (FEO) (p = 0.040) for IDD groups. Significant time main effects were reported for average M/L displacement (EO) (p = 0.001), (EC) (p = 0.004), (FEO) (p = 0.005), (FEC) (p = 0.004), and average A/P displacement (EO) (p = 0.006) and (FEO) (p = 0.005) for TD groups. An inclusive badminton program indicated evidence of improved static postural control for those with IDD. However, no significant differences were reported for TD peers.

Acute Effect of Heavy Load Back Squat and Foam Rolling on Vertical Jump Performance.

Purpose: In a rested state, foam rolling has been shown to improve blood flow to the working tissues. When inducing post-activation performance enhancement (PAPE), previous research suggests a longer recovery period between the conditioning activity and performance assessment in weaker participants (back squat <2.0 × body mass). It is possible that a cool-down effect may take place between the conditioning activity and performance assessment for these participants. Therefore, the purpose of this investigation was to determine if foam rolling could help mitigate any cool-down effect to help participants capitalize on PAPE. Methods: Seventeen physically active participants completed baseline jumps followed by rest (control), back squat exercise (heavy squats), rest and foam rolling (FR), and heavy squats followed by foam rolling (combo). VJ performance was assessed three times post-treatment with 2 min between each assessment. Results: VJ height and impulse were greater at baseline than at any other time point across all sessions (p < .001). Impulse for the control and FR sessions were greater than the squats session (p < .015). Impulse for the combo session was less than the FR session (p = .04). Conclusions: Foam rolling did not have a significant impact on attenuating any cool-down effect. In addition, our heavy squats protocol appears to induce too much fatigue that possibly masked the effects of PAPE.

Comparison of the Reliability of Four Different Movement Thresholds When Evaluating Vertical Jump Performance.

Analyzing vertical jumps performed on a force plate can be useful for the strength and conditioning professional in managing neuromuscular fatigue. The purpose of this study was to compare different movement thresholds when analyzing countermovement (CJ) and squat jump (SJ) performance. Twenty-one college-aged participants (9 female, 12 male) performed five CJs and five SJs. Movement initiation was identified when the vertical ground reaction force (VGRF) deviated five standard deviations (5SD), four standard deviations, (4SD), 2.5% of system weight (2.5%SW), and 10% of system weight (10%SW) from their starting position. For CJs, movement was determined when the VGRF deviated either above or below these thresholds (5SDAB, 4SDAB, 2.5%SWAB, 10%SWAB) and was compared to when VGRF deviated below these thresholds (5SDB, 4SDB, 2.5%SWB, 10%SWB) in terms of peak force (Fmax), net impulse (netIMP), braking impulse (brIMP), propulsive impulse, jump height (JHT), peak power (Pmax), peak velocity (Vmax), and RSImod. For SJs, movement was determined when VGRF initially rose above these thresholds (5SD, 4SD, 2.5%SW, and 10%SW) for Fmax, netIMP, JHT, and Vmax. Significant differences were observed among several methods except for Fmax. However, these differences were small. All CJ measures demonstrated good-to-excellent relative reliability (ICC: 0.790−0.990) except for netIMP for 2.5%SWAB (ICC: 0.479). All methods demonstrated good absolute reliability as measured by percent coefficient of variation (CV%) except brIMP and RSImod. This may be due to instructions given to each jumper as well as skill level. For SJs, no differences in Fmax or netIMP were found across all methods. Small differences were seen for JHT, Pmax, and Vmax across several methods. All methods produced acceptable CV% (<10%) and excellent ICCs (0.900−0.990). However, some jumpers produced CV% that was greater than 10% when determining JHT for 5SD, 4SD, and 2.5%SW methods. This could be due to our method of obtaining system weight. Based on our findings, we recommend using the 10%SW method for assessing SJ performance on a force plate.

Effects of a ten-second maximum voluntary contraction on regulatory myosin light-chain phosphorylation and dynamic performance measures.

The purpose of this investigation was to evaluate the role of an elevated regulatory myosin light-chain (RLC) phosphorylation on subsequent postactivation potentiation induced by a 10-second maximum voluntary contraction (MVC). With the use of a repeated measures design, data were collected from 11 recreationally active men who performed an explosive knee extension exercise with a load of 70% of their 1 repetition maximum. Muscle biopsies of their vastus lateralis were taken pre- and post-MVC. Seven subjects had elevated RLC phosphorylation (positive responders) and 4 had a decrease in RLC phosphorylation (negative responders). Percent change of force, velocity, and power measures did not differ between the 2 groups. Our results suggest that recreationally active men will not benefit from the effects of postactivation potentiation during performance with a 7-minute recovery period. Furthermore, we suggest that training status, strength, and skill level might be key determining factors for the positive benefits of postactivation potentiation during performance.

Contractile properties and myosin heavy chain composition of rat tongue retrusor musculature show changes in early adulthood after 19 days of artificial rearing.

Previously, we showed that artificial rearing using the "pup in a cup" model results in decreased tongue activity and caused some minor alterations in the tongue retrusor musculature. However, the artificial rearing time frame previously chosen was brief (11 days). The purpose of the present investigation was to extend the artificial rearing period from postnatal days 3 to 21 (P21) to determine whether significant alterations occur as a result of this reduced tongue use. Several changes in contractile properties due to the artificial rearing process were observed, which fully recovered by postnatal days 41 to 42 (P41-2). These changes included a shorter twitch contraction time, shorter twitch half-relaxation time, and decreased fatigue resistance. Styloglossus muscle exhibited more neonatal myosin heavy chain (MHC) isoform at P21 for the artificially reared (AR) group. Changes that were persistent at P41-2 were also observed. Maximum tetanic tension was lower for the AR group at P21 and P41-2 compared with their dam-reared counterparts. Twitch tension was also lower by P41-2 in the AR group. At P41-2, the AR group exhibited an increase in MHC IIa and a decrease in MHC IIb for the styloglossus muscle. In addition, the AR group exhibited a decreased MHC IIb for the long head of the biceps brachii at P41-2. Our results are similar to other models of hindlimb immobilization and suspension. By extending our artificial rearing period, this reduced tongue activity induced acute changes and alterations in the tongue retrusor musculature that persisted into early adulthood.

Effects of 12 days of artificial rearing on morphology of hypoglossal motoneurons innervating tongue retrusors in rat.

The purpose of this study was to examine the influence of reduced tongue activity by artificial rearing on the morphology of motoneurons innervating the extrinsic tongue retrusors. Artificially reared rat pups were fed via gastric cannula from postnatal day 3 to postnatal day 14. Artificially reared animals and dam-reared controls had cholera toxin (subunit B) conjugate of horseradish peroxidase injected into the styloglossus to label motoneurons innervating hyoglossus and styloglossus on postnatal day 13 and postnatal day 59. Following perfusion on postnatal days 14 and 60, serial transverse sections treated with tetramethyl benzidine and counterstained neutral red were used to analyze motoneuron morphology. The shorter diameter of hyoglossus motoneurons increased with age for the dam-reared but not the artificially reared group. There was a tendency for a similar pattern for styloglossus motoneurons across the two rearing groups. The changes in form factor reflected the changes in shorter diameter for both motoneuron pools. Therefore, reducing suckling activity during normal postnatal development leads to diminished motoneuron somal growth in rats. This may also be the case in premature infants necessarily fed artificially.

Myosin heavy chain and fibre diameter of extrinsic tongue muscles in rhesus monkey.

OBJECTIVE: The purpose of this investigation was to identify the myosin heavy chain (MHC) phenotype and fibre diameters of hypoglossal innervated extrinsic tongue muscles in rhesus monkey. METHODS: Genioglossus, styloglossus and hyoglossus muscle samples obtained from three female rhesus monkeys were analysed for MHC isoforms via gel electrophoresis and stained with MHC antibodies to measure least mean diameters. RESULTS: MHC phenotypes were consistent for all three muscles. Each muscle was predominantly composed of MHC type IIa and I. All three isoforms were significantly different from each other in fibre diameter for styloglossus and genioglossus (IIb>IIa and IIx>I; P<0.001). For hyoglossus, the MHC type II isoforms had larger diameters than the MHC type I isoform (P<0.001). CONCLUSIONS: While the extrinsic tongue muscle MHC and/or muscle fibre type composition may be different between mammalian species, there are consistent similarities between the intrinsic and extrinsic tongue muscles. We suggest this is necessary for the highly coordinated activities performed by the tongue such as mastication, respiration and swallowing. The differences in fibre diameters among MHC isoforms suggest a large force gradation, which would be consistent with the coordination of these activities. The similarities among primates in MHC and/or muscle fibre composition as well as similar cortical inputs to the hypoglossal nucleus, suggest that we could expect to see similar MHC phenotype for extrinsic tongue muscles in human.

Phenotype and contractile properties of mammalian tongue muscles innervated by the hypoglossal nerve.

The XIIth cranial nerve plays a role in chewing, respiration, suckling, swallowing, and speech [Lowe, A.A., 1981. The neural regulation of tongue movements. Prog. Neurobiol. 15, 295-344.]. The muscles innervated by this nerve are functionally subdivided into three categories: those causing protrusion, retrusion, and changing the shape of the tongue. Myosin heavy chain (MHC) II isoform makes up the majority of the MHC phenotype with some variability among mammalian species and some evidence suggests between genders. In addition, there are regional differences in fiber type within some of these muscles that suggest functional compartmentalization. The transition from developmental MHC isoforms to their adult phenotype appears to vary not only from muscle to muscle but also from species to species. Motor units within this hypoglossal motor system can be categorized as predominantly fast fatigue resistant. Based on twitch contraction time and fatigue index, it appears that hypoglossal innervated muscles are more similar to fast-twitch muscles innervated by spinal nerves than, for example, extraocular muscles.

Postnatal development of hypoglossal motoneurons that innervate the hyoglossus and styloglossus muscles in rat.

Postnatal development of hyoglossus and styloglossus motoneurons was studied in this investigation of the hypoglossal nucleus. Our findings show separate and distinct locations for hyoglossus and styloglossus motoneurons within the retrusor (dorsal) subdivision of the hypoglossal nucleus for all age groups. Hyoglossus and styloglossus motoneuron cross-sectional area reached their adult size at different times (by weeks 2 and 3, respectively). Cell roundness, as measured by form factor (measure of cell perimeter relative to its area), decreased with advancing postnatal age for both populations of motoneurons. Differences in the direction of the dendritic projection between hyoglossus and styloglossus motoneurons were found. Hyoglossus and styloglossus motoneuron development was compared to genioglossus motoneuron postnatal development.

Effect of knee position on hip and knee torques during the barbell squat.

UNLABELLED: Some recommendations suggest keeping the shank as vertical as possible during the barbell squat, thus keeping the knees from moving past the toes. This study examined joint kinetics occurring when forward displacement of the knees is restricted vs. when such movement is not restricted. Seven weight-trained men (mean +/- SD; age = 27.9 +/- 5.2 years) were videotaped while performing 2 variations of parallel barbell squats (barbell load = body weight). Either the knees were permitted to move anteriorly past the toes (unrestricted) or a wooden barrier prevented the knees from moving anteriorly past the toes (restricted). Differences resulted between static knee and hip torques for both types of squat as well as when both squat variations were compared with each other (p < 0.05). For the unrestricted squat, knee torque (N.m; mean +/- SD) = 150.1 +/- 50.8 and hip torque = 28.2 +/- 65.0. For the restricted squat, knee torque = 117.3 +/- 34.2 and hip torque = 302.7 +/- 71.2. Restricted squats also produced more anterior lean of the trunk and shank and a greater internal angle at the knees and ankles. The squat technique used can affect the distribution of forces between the knees and hips and on the kinematic properties of the exercise. PRACTICAL APPLICATIONS: Although restricting forward movement of the knees may minimize stress on the knees, it is likely that forces are inappropriately transferred to the hips and low-back region. Thus, appropriate joint loading during this exercise may require the knees to move slightly past the toes.