An acute increase in maximum strength, power, or speed following a conditioning contraction known as a postactivation performance enhancement has been previously determined to be better performed ...when the initial exercise is of the same movement pattern. However, no research has been performed studying the effects of a hex-bar farmer’s walk on subsequent sprinting speeds. Therefore, this research examined the use of different loads of a hex-bar farmer’s walk completed at 20-m and their effect on subsequent 20-m sprinting performance. Through a randomized and counterbalanced design, resistance and running trained men and women (n = 12) performed five 20-m sprints (with 10-m splits) at baseline, 4, 8, 12, and 16-minutes after a bodyweight control (C), light farmer’s walk (LFW), and heavy farmer’s walk (HFW), utilizing 70% and 80% users hex-bar deadlift 1-RM respectively. Mean sprint velocities over 10-m and 20-m distances were similar at baseline. At 20-m, sprint velocity significantly increased during the LFW condition at 8 minutes (M = 6.03, SE = 0.14, p = 0.025), 12 minutes (M = 6.05, SE = 0.15, p = 0.016), and 16 minutes (M = 6.03, SE = 0.14, p = 0.011) when compared with C (M = 5.96, SE = 0.14, t(11) = -2.59, r = 0.98); (M = 5.97, SE = 0.15, t(11) = -2.85, r = 0.98); (M = 5.94, SE = 0.14, t(11) = -3.06, r = 0.98, p < 0.05). At 10-m, sprint velocity significantly increased during the LFW condition at 8 minutes (M = 5.10, SE = 0.12, p = 0.010), when compared with C (M = 5.01, SE = 0.12, t(11) = -3.08, p <0.05, r = 0.97). No change to sprinting velocity was witnessed across either of the C conditions or HFW conditions. These results help to substantiate the use of a load at near-maximal capacities during the warm-up preceding sprinting to acutely increase muscular force.
Countermovement jumps (CMJ) are frequently used in strength and conditioning as a key performance indicator. Force platforms are often considered the standard for measuring ground reaction forces ...(GRF) and deriving subsequent performance metrics. Although force platforms are often the standard, they may not always fall within an allotted budget. Jump mats are another option for CMJ testing that are cheaper than the criterion force plates. Although cheaper, jump mats only measure flight time (FT) and jump height (JH), whereas the criterion measures GRF. Therefore, this study looks at the reliability and validity of the Just Jump System compared to the criterion reference ForceDecks force plates during a CMJ with a self-selected depth. This study examined the agreement between the metrics: jump mat FT to force plate FT, jump mat JH to force plate JH, jump mat JH derived by FT to force plate JH derived by impulse. Twelve participants (male n=7 and female n=5 with an average age of 24 years SD 3, average body mass of 83.7 kilograms SD 17.5, average height of 176.2 centimeters SD 11, and an average shoe thickness of 1.8 centimeters SD .5) completed a standardized warmup including a familiarization protocol. Following, the participant completed 5 sets of 5 repetitions of CMJ. Each repetition was followed by a 30 second rest period. Each set of 5 jumps was followed by two minutes of rest. Force plate data was analyzed in the proprietary ForceDecks software, and then exported to excel. Jump mat data was manually recorded on a data collection sheet which was then manually entered into excel. From excel, an interclass correlation coefficient (ICC) and the coefficient of variation (CV) for reliability were calculated. The ICC was reported as .96 and the CV was reported as 9.16%. These results indicated that the Just Jump mats have excellent reliability. For validity, means and standard deviations, a Pearson’s correlation, coefficient of determination, scatter plots, and a Bland-Altman 95% limits of agreement (LOA) were utilized. The means and standard deviations reported by the jump mat were flight time (ms) 541.37 (SD 49.64), jump height (cm) 36.74 (SD 6.79). The means and standard deviations reported by the force platforms were flight time (ms) 446.87 (SD 52.60), jump height derived by flight time (cm) 24.82 (SD 5.91), and jump height derived by impulse (cm) 24.69 (SD 5.83). The Pearson’s correlation indicated a very strong positive relationship with all metrics where force plate FT and jump mat FT (r = 0.991), force plate JH derived by FT and jump mat JH (r= 0.995), force plate JH derived by impulse and jump mat JH (r = 0.974). The Bland-Altman 95% limits of agreement (LOA) analysis between force plate FT and jump mat FT showed a mean bias ± LOA of 1.80 (LOA 14.77 ms). The Bland-Altman 95% LOA analysis between force plate JH derived by FT and jump mat JH showed a mean bias ± LOA of 2.02 (LOA 2.14 cm). The Bland-Altman 95% LOA analysis between force plate JH derived by impulse and jump mat JH showed a mean bias ± LOA of 2.07 (LOA 3.37 cm). The Just Jump mat overestimates FT, and thus, overestimates JH. Although reliable, the Just Jump mats are not valid in comparison to the criterion force plates.
HintergrundZur Bestimmung der therapeutischen Impulsrichtung bei der Atlastherapie nach Arlen gilt die Anfertigung einer a.-p.-Röntgenaufnahme des zervikookzipitalen Übergangs traditionell als ...unverzichtbar. Überlegungen zum Strahlenschutz sowie technische und ökonomische Aspekte förderten die Suche nach einer klinischen Methode, die in der Lage ist, die radiologische Untersuchung zu ersetzen. Zur Diskussion stand der manualdiagnostische 3-Zeichen-Test nach CoenenMethodikDie Zuverlässigkeit des 3-Zeichen-Tests wurde an 438 neurologisch gesunden Patienten mit Funktionsstörung der oberen Halswirbelsäule (HWS) untersucht. Das Testergebnis jedes einzelnen Patienten wurde mit der Analyse seiner Atlas-a.-p.-Röntgenaufnahme verglichen. Jeder Patient erhielt die Atlastherapie nach Arlen gemäß dem 3-Zeichen-Test-Ergebnis; die Bestimmung der Sensitivität des Tests erfolgte aus dem Therapieergebnis nach einmaliger Behandlung.ErgebnisseEine Übereinstimmung des 3-Zeichen-Tests mit der Röntgenbildanalyse ergab sich bei 84,6 % der untersuchten Patienten, keine Übereinstimmung fand sich bei 8,5 % und unklar blieben 6,3 %. Eine Bestätigung des Tests durch das Therapieergebnis nach einmaliger Behandlung wurde bei 94,5 % der Patienten ermittelt, bei 5,3 % fand sich keine Bestätigung.SchlussfolgerungBei der Bestimmung der atlastherapeutischen Impulsrichtung erwies sich der 3-Zeichen-Test als mindestens gleichwertig mit der Röntgenbildanalyse. Der Test kann somit die rein therapeutisch indizierte Röntgenuntersuchung des zervikookzipitalen Übergangs ersetzen und leistet einen wichtigen Beitrag zur Minderung der Strahlenexposition. Er ist kein Ersatz für eine diagnostische Röntgenaufnahme zum Ausschluss pathologischer Prozesse an der HWS bei auffälliger Anamnese und suspekter Symptomatik.
The purpose of this study was to examine the influence of unstructured daily play participation on chronic and perceived stress patterns and obesity prevalence in elementary school children compared ...to children receiving standard recess time in elementary schools. Fourth grade students (n=130) from six north Texas public schools were assessed using the Stress in Children (SiC) Questionnaire, hair cortisol concentration, body fat percentage, and whether they engaged in 30 minutes or 45 minutes of unstructured play daily. Three schools of students (control; n=66) engaged in 30 minutes of recess daily and three schools of students (intervention; n=64) engaged in 45 minutes of recess daily. SiC questionnaires were administered to each participant on an electronic device via Qualtrics to obtain their perceived chronic stress level. Hair samples were collected to assess the actual chronic cortisol level in each child. The cortisol was analyzed using ELISA protocol following cortisol extraction procedures. Bioelectrical impedance scales were used to collect fat percentage of each student. Previous research shows the average 9-year-old will have a hair cortisol level of 6.7 pg/mg, and the average 10-year-old will have a hair cortisol level of 8.5 pg/mg. An independent samples t-test showed the intervention group was significantly less chronically stressed than the control group (p = .018). The intervention students showed below average levels of chronic stress (9-year-olds = 6.27 pg/mg and 10-year-olds = 3.67 pg/mg) while the control school children were at or above average levels of chronic stress (9-year-olds = 20.89 pg/mg and 10-year-olds = 13.16 pg/mg). No significant group differences were found in SiC scores or body fat percentages (>.05) of participants. Overall, findings suggest 45 minutes of unstructured, outdoor play has a positive impact on lowering chronic cortisol levels. For children participating in at least 30 minutes of unstructured, outdoor play, body fat levels, on average, will be healthy, but 45 minutes is significantly more beneficial for decreasing and managing chronic stress.
Chapter 1: Molecular Mechanism of Mitochondrial Fragmentation and Glucose Metabolism under Disturbed Flow in Endothelial Cells: Focus on the Role of Dynamin-Related Protein 1. The luminal surface of ...the endothelium is continually exposed to dynamic blood flow patterns that is known to alter immunometabolic phenotypes of the endothelial cells (ECs). Recent literature reported that inhibition of the metabolic reprogramming to glycolysis or enhancement of oxidative phosphorylation (OXPHOS) is considered as an effective strategy to prevent EC proinflammatory activation and eventually the progression of vascular diseases. Endothelial mitochondria are highly dynamic organelles playing versatile roles in maintaining endothelial cell homeostasis working as bioenergetic, biosynthetic, and signaling organelles. The balance between fusion and fission processes modulates mitochondrial network, which is essential for maintaining mitochondrial homeostasis. Disruption of the orchestrated balance, especially toward excessive fission resulting in fragmented and dysfunctional mitochondria, has been shown to be associated with atheroprone phenotypes of ECs. However, there is a key knowledge gap with respect to morphology of EC mitochondria under different flow conditions and its role on EC immunometabolic phenotypes. In chapter 1, the purpose of this study was to investigate the effect of different flow patterns on mitochondrial morphology in ECs and its implication in immunometabolic endothelial phenotype. The overarching hypothesis of the Chapter 1 was that disturbed flow (DF) will increase mitochondrial fragmentation, which will facilitate glycolysis and inflammatory activation in ECs. In the study, mitochondrial morphology was analyzed in ECs at multiple segments of the aorta and arteries in EC-specific photo-activatable mitochondria (EC-PhAM) mice. Increased mitochondrial fragmentation was observed at atheroprone regions (e.g., lesser curvature of the aortic arch, LC) with increased dynamin-related protein 1 (Drp1) activity, compared with the atheroprotective regions (e.g., thoracic aorta, TA). The atheroprone regions also showed a higher level of endothelial activation and glycolysis. Carotid artery partial ligation surgery, as a surgical model of DF, significantly induced mitochondrial fragmentation with elevated Drp1 activity and increased EC activation. in vitro experiments recapitulated in vivo observations. Inhibition of Drp1 activity by mdivi-1 attenuated the DF-induced atheroprone EC phenotypes, showing the close relationship between mitochondrial morphology and atheroprone phenotypes of ECs. As for the molecular mechanism, hypoxia-inducible factor 1 α (HIF-1α) stabilization and its nuclear translocation was significantly increased under DF, which was attenuated by mdivi-1 treatment. Mitochondrial reactive oxygen species (mtROS) and succinate, which are known to reduce prolyl hydroxylase domain 2 (PHD2) activity thereby increasing HIF-1α stabilization, were significantly elevated under DF, but those were attenuated by mdivi-1 treatment. Finally, a 7-week voluntary wheel-running exercise training significantly decreased mitochondrial fragmentation with a down-regulation of VCAM-1 expression at the LC. In conclusion, our data suggest that DF induces mitochondrial fragmentation with increased Drp1 activity, which is associated with an atheroprone EC phenotype. In addition, regular practice of aerobic exercise reduces mitochondrial fragmentation and prevents ECs from an atheroprone endothelial phenotype at the atheroprone regions.Chapter 2: Molecular Mechanisms for Unidirectional Flow (UF)/Exercise-Induced improvement of Mitochondrial Integrity: Focus on phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1) /PARKIN-Dependent Mitochondrial Autophagy (Mitophagy). Phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1) is an essential molecule in the mitophagy process and known to act as a cytoprotective protein involved in several cellular mechanisms in mammalian cells. It has been documented that the loss of PINK1 expression in mice and various cell types enhance susceptibility to stress-induced cell damage, while the overexpression of PINK1 significantly attenuates stress-induced mitochondrial and cellular dysfunction. In chapter 2, the purpose of this study was to investigate PINK1 expression and its subcellular localization under an exercise-mimic laminar shear stress (LSS) condition in human primary endothelial cells and in exercizing mice, and its implications on endothelial homeostasis and cardiovascular disease (CVD) prevention. The overarching hypothesis of the Chapter 2 was that unidirectional flow (UF) will increase cytosolic PINK1 expression through which UF-preconditioned ECs will be more protective against an accumulation of dysfunctional mitochondria via a greater mitophagy induction. In this study, we measured the full-length PINK1 (FL-PINK1) mRNA and protein expression levels in ECs under unidirectional laminar shear stress (LSS). LSS significantly elevated both FL-PINK1 mRNA and protein expressions in ECs. Mitochondrial fractionation assays showed a decrease in FL-PINK1 accumulation in the mitochondria with an increase in the cytosolic FL-PINK1 level under LSS. Confocal microscopic analysis confirmed these subcellular localization patterns suggesting downregulation of mitophagy induction. Indeed, mitophagy flux was decreased under LSS, determined by a mtKeima probe. Mitochondrial morphometric analysis and mitochondrial membrane potential determined by tetraethylbenzimidazolylcarbocyanine iodide (JC-1) showed mitochondrial elongation and increased mitochondrial membrane potential under LSS respectively, suggesting that an elevation of cytosolic PINK1 is not related to an immediate induction of mitophagy. However, increased cytosolic PINK1 elevated mitophagic sensitivity toward dysfunctional mitochondria in pathological conditions. Preconditioned ECs with LSS showed lower mtDNA lesions under angiotensin II stimulation. Moreover, LSS-preconditioned ECs showed rapid Parkin recruitment and mitophagy induction in response to mitochondrial toxin (i.e., carbonyl cyanide chlorophenylhydrazone, CCCP) treatment compared to the control. We measured PINK1 expression at ECs of the thoracic aorta in exercised mice, a physiological LSS-enhanced model, which was significantly elevated compared to sedentary animals. In addition, exercise-preconditioned mice were more protective to angiotensin II-induced mtDNA lesion formation in the mouse abdominal aorta than sedentary mice, suggesting a potential protective mechanism of exercise in a PINK1-dependent manner. In conclusion, LSS increases a cytosolic pool of FL-PINK1, which may elevate the mitophagic sensitivity toward dysfunctional mitochondria or activate other cytoprotective mechanisms in ECs. Our data suggest that exercise may support mitochondrial homeostasis in vascular ECs by enhancing PINK1-dependent cell protection mechanisms.
This study aims to improve a soccer player’s shot on goal by applying a core exercise intervention to determine its influence on balance, absolute strength, and shot accuracy. Collegiate soccer ...players (N=20) were tested at baseline and after twenty days. Balance was measured using the Star Excursion Balance Test (SEBT) and the Y Balance Test (YBT). Participant shot accuracy was measured using an accuracy net that includes multiple targets. Absolute strength was measured using a one repetition maximum (1RM) bench press test and squat test, and endurance measured using a plank hold test. The control group (CTRL, n=10) continued with activities of daily living (ADL), including regular soccer practices, without implementing a core exercise intervention. The intervention group (INT, n=10) completed a core exercise intervention program consisting of unilateral, dynamic balance exercises. Following the twenty-day intervention period, both groups were tested in all metrics again to determine if any changes occurred. Data were analyzed to determine if balance improved in the core intervention group in the posterior and lateral reaches, as well as their overall strength. Although the results did not indicate significant differences in shot accuracy, the study encourages further research because posterior balance significantly improved in the INT group but not CTRL in all balance tests. Future core intervention may include exercises to improve anterior and medial balance to determine if accuracy is improved by a core intervention program.
This dissertation included two investigations with the overall aim of increasing available knowledge on the effects of napping on physical and cognitive performance of physically active and athletic ...individuals. First, a systematic review with meta-analysis was conducted to quantify the effects of experimental studies examining the influence of napping on physical performance, and to identify potential moderator variables. Sixty-one effects derived from 20 studies of predominantly young men resulted in a small, positive, and statistically significant mean effect (Δ = 0.38, 95% CI = 0.24-0.52). Univariate analyses demonstrated significant positive effects for repeated sprint (Δ = 0.40, 95% CI = 0.01-0.80) and shuttle run performance (Δ = 0.54, 95% CI = 0.30-0.78). Only 5 studies objectively assessed sleep duration during the nap opportunity, and moderator analyses found larger effects when the nap duration was not confirmed objectively (Δ = 0.49, 95% CI = 0.33-0.65) compared to naps measured with accelerometry or electroencephalography (Δ = 0.05, 95% CI = -0.23-0.33). No differences in effect size were reported for nap opportunity duration, normal versus restricted prior sleep, time of day variables, or participant physical training status. However, preliminary quantitative evidence and direct comparison studies suggest the potential for these variables to influence the effects of a nap on physical performance.Secondly, an experiment was conducted to test the effect of a nap on physical performance, specifically seeking to address several gaps in the literature identified by the systematic review and meta-analysis. Normally sleeping physically active women (n =19) completed two randomly ordered conditions one week apart: a no-nap control and 45-minute nap opportunity. Outcomes of physical and cognitive performance were measured with the 3-minute burpee test (3-MBT) and the digit-cancellation test (DCT). The nap resulted in increased 3-MBT performance while DCT scores were unaffected.In total, the evidence accumulated in this dissertation support the efficacy of napping to enhance physical performance for active and athletic individuals. In contrast to prior studies, this dissertation did not find a nap to benefit digit-cancellation performance. More research is needed to better understand how the effects of napping vary across diverse groups, athletic settings and circumstances.
16 participants participated in a 4 week (12 session) balance training protocol. Pre and post-testing used a gait assessment to examine margin of stability and center of pressure. Senaptec sensory ...station was used to examine the relationship between variables of interest and visual skills. 4 groups were distinguished by stable and unstable surfaces and eyes open and eyes closed. There was no relationship between variables of interest and surface type or visual condition.
Context: Posterior shoulder tightness is common among collegiate overhead athletes due to repetitive overhead patterns, often resulting in altered range of motion patterns. This may be associated ...with additional non-painful hypersensitive areas of taut muscle called latent myofascial trigger points (LTrPs), which have been linked to muscle imbalances, muscular weaknesses, impaired motor recruitment, and internal rotation (IR) range of motion (ROM) deficits. Evidence supports improvements in glenohumeral ROM and isometric strength through instrument assisted manual therapy techniques on MTrPs in baseball players. Ischemic compression (IC) is a form of therapeutic myofascial release that can be performed by any clinician trained in manual therapy. Although improvement in ROM and isometric strength have been indicated within other regions of the body, it is unknown if IC treatment of LTrPs will improve glenohumeral ROM and isometric strength in overhead athletes. Objective: The purpose of this study was to determine the relationship between short- and long-term repeated IR ROM and ER isometric strength measurements before and after IC treatment compared to sham compression. Study Design and Setting: Single-blinded randomized controlled trial in a controlled athletic training laboratory. Patients or Other Participants: Forty healthy Division I collegiate overhead athletes (age: 20.3 ± 1.6 years) from baseball, cheer, circus, softball, swimming, track and field, and volleyball were included in this study. Participants were excluded if they did not have a total arc ROM deficit of ≥ 5° in the dominant shoulder compared to the ideal 180° for overhead athletes or deficits of ≥ 20° of IR compared to the contralateral shoulder, had at least two LTrPs in the dominant shoulder infraspinatus muscle, or scored < 70% on the Kerlan-Jobe Orthopedic Clinic scores (KJOC) or Penn Shoulder Scores (PSS) questionnaires. Intervention: Participants were randomly allocated to one of two intervention groups; IC or sham IC. Participants in the IC group completed passive IR glenohumeral ROM and ER isometric strength measurements before and immediately after IC treatment session #1, within 24–48 hours of IC treatment session #1, and final measurements taken within 24–48 hours after IC treatment session #2. The sham IC group completed the same procedures as the IC group, except investigators did not apply manual pressure to MTrPs. Main Outcome Measures: Passive glenohumeral IR ROM, ER isometric strength, and pain-pressure threshold (measured by a digital pressure algometer). The KJOC and PSS were used to determine each participant’s perceived level of dominant shoulder function before and after interventions. Results: Dominant shoulder passive glenohumeral IR ROM did not increase following the IC or sham interventions. Individuals who received IC did not demonstrate significant ER strength gains compared to baseline, but individuals who received sham compression demonstrated a significant decrease in overall ER isometric strength during the final measurement time-point compared with baseline (–1.63 ± 1.93) versus the IC group (–0.20 ± 1.66; F(1, 28) = 6.32, p = 0.016, η2p = 0.17). Pain-pressure threshold showed a greater decrease in the 1st LTrP at the first post-intervention time-point compared to baseline in the IC group (–1.49 ± 1.56) versus sham (–0.53 ± 1.23, F(1, 28) = 4.68, p = 0.037). No differences in pain-pressure threshold in the first LTrP were found at the other time-points. Conclusion: Our findings suggest that ischemic compression may not be an effective treatment method for improving glenohumeral IR ROM and/or ER isometric strength. Additional research is required to completely understand, implement, and/or rule out the use of ischemic compression on LTrPs as a treatment for glenohumeral IR ROM and ER isometric strength in healthy collegiate overhead athletes.
PURPOSE: The purpose of this study was to compare the effects of 8 weeks performing various resistance training protocols with and without blood flow restriction (BFR) on muscular strength, body ...composition, arterial elasticity, and hemodynamics responses in young males. RESULTS: Significant time*condition interactions occurred in HR period (p <0.05), HDI SBP (p <0.05), HDI MAP (p <0.05), and SV (p <0.05). Trends for time*condition interactions were found in HDI DBP (p=0.054), HDI HR (p=0.051), and HDI SVR (p=0.085). Significant time main effects occurred in all strength measures (p <0.05). Significant condition main effects occurred in Aortic DBP (p <0.05), Brachial DBP (p <0.05), and LAE (p <0.05). Total lean mass significantly increased from baseline the HI condition only (p<0.05).CONCLUSION: Significant improvements in lean mass were seen following the HI and BFR protocols. However, decreases in LAE were found following the HI protocol only. It appears that performing aerobic exercise after resistance training can negatively affect muscle growth. However, only 15 min of moderate-intensity aerobic training can improve hemodynamics in young, healthy males. Improvements in SBP, DBP, SVR, MAP, HR and SV were seen following the HI+AE protocol. KEYWORDS: Blood flow restriction, pulse wave velocity, arterial elasticity
