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.
Many youth athletes and their parents focus specifically on baseball with the belief that it will aid with obtaining a college scholarship and maybe even reach the professional level. However, ...evidence shows that this can increase injury risk and injury in these young developing skeletons. The literature also suggests that educating parents could reduce these injuries. Using a web-based survey and educational video, this study aimed at educating parents on injury risk and prevention guidelines. A total of 32 parents completed the pre-survey, answering questions about their familiarity with potential youth injuries, current practices, and familiarity and knowledge of the Pitch Smart guidelines. Parents were then asked to watch an educational video covering potential injuries and Pitch Smart guidelines. Once viewed, parents (n=8) completed the post-survey, which asked the same knowledge questions. To increase participants, college athletes were invited to participate as well; 13 started the pre-survey but only 4 completed the post-survey. Parents increased significantly on their overall knowledge score (pre-survey: 11.6 ± 2.77, post-survey: 16.0 ± 1.60, t(7) = -5.79, p<.001) as well as injury familiarity after the educational video, while there was little improvement in the college athletes. Responses on the post-survey evaluation were positive but suggested the video was too long and could have benefited from format changes. Further research with larger samples is needed to develop effective educational programs and delivery methods.
Endurance sports, including running, cycling, and swimming, remain popular among recreational athletes in the U.S. and across the world. Many of these athletes compete in local, regional, and ...national races throughout the year. Their performance in competitions is affected by many factors, including genetics, nutrition, and training. Often, recreational athletes receive conflicting recommendations regarding strategies to optimize performance. Direct-to-consumer genetic testing companies promise to give insights into supposed genetic markers of endurance ability; blogs and social media tout the latest diet strategies to lose weight and perform better; virtual coaches and performance-improvement websites sell training plans with sometimes contradictory training strategies. It remains unclear which of these strategies actually benefit endurance athletes. Therefore, this dissertation examined the effects of genetics, diet composition, and training characteristics on endurance performance in recreational athletes, who often spend a considerable percentage of their disposable income and their time on improving race outcomes.Single-nucleotide polymorphisms (SNPs), variations in a single base pair of a gene, have been proposed to affect physical performance. A SNP in the ACTN3 gene (XX genotype), results in deficiency of α-actinin-3, a structural muscle protein that appears important for explosive movements. Studies in rodents suggest that this deficiency could be beneficial for endurance performance. Yet, few studies in humans have directly assessed the effects of ACTN3 genotype on endurance performance. In our first study, we compared self-reported 1-mile and 5-km running personal records (PR) between participants expressing the three different ACTN3 genotypes. Among women, those with the ACTN3 XX genotype reported faster 1-mile PRs compared to those with the RR and RX genotype. We found no differences between genotypes for 1-mile PRs among men or 5-km PRs among either sex.A long-standing strategy to improve endurance performance is to increase carbohydrate (CHO) availability before and during competition to slow the fatigue process. An opposing approach introduced by researchers, coaches, and athletes, is to increase fat oxidation (FATox) capacities by employing a low-CHO or ketogenic diet (KD). This improved ability for FATox at typical race-intensities would open access to an essentially limitless supply of energy substrates stored in the body as fat. However, studies investigating the effects of KD and high-CHO diets (HC) on endurance performance have found conflicting results. In our second study, participants followed an HC and a KD for two weeks each in a random order. They performed a simulated 30-km cycling time trial (TT) at baseline and following each intervention. Participants’ average power output or endurance performance during the TT was substantially lower following the KD when compared with the HC.Endurance training is the main mechanism to improve general cardiorespiratory fitness and performance in races. Training characteristics include frequency, volume, intensity, and training intensity distribution (TID). TID can be determined by the time spent in the easy (Zone 1), moderate (Zone 2), and hard (Zone 3) training zones. Recently, a polarized TID (time in Z1 > Z3 > Z2) has gained popularity, after research suggested that many elite endurance athletes appear to follow this approach. However, the TID employed by recreational athletes and its association with performance is unknown. In our third study, we analyzed the training characteristics of recreational cyclists and triathletes. We investigated their association with endurance performance as measured by estimated relative critical power (CPrel). In our sample, very few recreational athletes followed a polarized TID. When controlling for age, we found that increased training volume and polarization were positively associated with CPrel.In conclusion, ACTN3 genotype does not appear to have a strong effect on endurance performance. Our results, along with findings from other studies investigating so-called endurance SNPs, suggest that individual genetic markers are not good indicators of endurance performance ability; thus, athletes and coaches should not rely upon direct-to-consumer genetic testing for talent identification and sport selection. Further, based on the results of our second study, the KD appears to decrease endurance performance. While additional research using longer nutrition interventions and different performance measures is needed, it appears that maximizing CHO availability remains the best strategy to improve endurance performance. Finally, we found that few recreational athletes follow a polarized TID despite its potentially beneficial effect on performance.
This study examined whether accuracy of intraset RIR predictions changes over time. Nine resistance trained men completed three bench press training sessions per week for six weeks, with the last set ...of each session performed until muscular failure. During the set to failure, subjects verbally indicated when they perceived 4 repetitions in reserve (RIR) and 1 RIR during the set. For each RIR prediction, the difference between perceived RIR and actual RIR was calculated as RIRDIFF. We analyzed differences in RIRDIFF using both the raw RIRDIFF (including positive and negative values) and the absolute values of all RIRDIFF using a factorial MANOVA. Covariates included proximity to failure of the RIR prediction, total repetitions performed per set, percentage of one-repetition maximum lifted, the week of training, and the session (1, 2, or 3 within each seek). For the raw RIRDIFF all covariates, except for percentage of 1RM (p > 0.05) were significantly related to the outcome measure at both the predicted 4 and 1 RIR (p < 0.001 to p = 0.04). Specifically, RIRDIFF was significantly higher in weeks 1–4 versus weeks 5–6 (p < 0.001 to p = 0.005). However, the only covariate which significantly impacted the absolute value RIRDIFF at both the predicted 4 (p = 0.033) and 1 RIR (p = 0.022) was total repetitions per set. These results indicate that trained men tend to shift from overpredicting to underpredicting RIR over time and that more repetitions in a set is related to more inaccurate RIR predictions. However, the actual accuracy (i.e., absolute value RIRDIFF) did not significantly change over six weeks of training.
The influence of autonomic nervous system (ANS) activity on the development and progression of cardiovascular disease (CVD) is widely acknowledged, as most common CVD risk factors (e.g., ...hypertension, impaired glucose management, obesity, low cardiovascular fitness) affect and/or are affected by ANS activity. Increased adiposity can be viewed as an amplifier of CVD development, as it has been shown to elevate the chances of developing hypertension and diabetes mellitus. Thus, adiposity may have direct and indirect effects on CVD development. In turn, it is important to determine if similar multidirectional relations can be observed between adiposity and altered ANS activity. Therefore, this dissertation addressed two main goals. The first was to evaluate the direct and indirect influence of adiposity on ANS activity through secondary data analyses employing structural equation modeling in a large, population-based cohort. The parasympathetic and sympathetic branches of the ANS were noninvasively assessed via heart rate variability reflected by root mean square of successive differences between normal beats (RMSSD) and the pre-ejection period of systole (PEP); measured via impedance cardiography, respectively. The direct effects of adiposity on ANS activity were assessed by examining the magnitude of influence of waist circumference (WC) on RMSSD and PEP. Indirect effects were assessed via the impact of WC on the latent variables of glycemic impairment (GI; fasting blood glucose and insulin concentrations, hemoglobin glycosylation percentage) and cardiac stress (CS; heart rate, diastolic blood pressure) parameters. Adiposity had both significant direct (β = 0.208, p = 0.018) and indirect (β = -.217, p=.041) effects on PEP through GI. Adiposity displayed no significant direct effect on RMSSD. CS displayed a significant pathway (β = -0.524, p = 0.035) on RMSSD, but the indirect effect of WC on RMSSD through CS was not significant. These results suggest that adiposity’s relation to ANS activity is multifaceted, as increased central adiposity had opposing direct and indirect effects on markers of sympathetic activity in this population of older adults. The second goal of this dissertation was to determine if cardiovascular fitness, as determined through graded exercise testing, influenced the relation of adiposity and ANS activity beyond the role it plays in determining adiposity, per se. To accomplish this goal, ANS activity was examined in a small cohort of young males with a range of fitness and adiposity levels before and after maximal aerobic exercise. A mixed model analysis of covariance was employed to test the additional impact of cardiovascular fitness on the relations between adiposity and ANS activity at rest and following maximal exercise. Group stratification by waist circumference or body fat percentage (BF%) revealed no across-group differences in resting or post-maximal exercise HRV or PEP measurements. Accounting for weight-relative peak oxygen uptake (VO2peak) resulted in significant between-group differences in the natural logarithm SDNN (ln-SDNN), RMSSD (ln-RMSSD), and high frequency spectral power (ln-HF) at 3- and 5-minutes post-exercise when groups were stratified by BF%. However, these differences were no longer statistically significant following adjustments for lean body weight-relative VO2peak, suggesting no effect of BF% on ANS activity. These results provide evidence that there may not be differences in resting ANS activity and post-maximal exercise ANS responsiveness across adiposity groups in apparently healthy males. Taken together, these two studies highlight the nuanced involvement of adiposity on physiological parameters that influence ANS activity. However, they do not support the notion that adiposity has a strong, independent influence on ANS activity.
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
BACKGROUND: Recent studies have shown that high intensity interval training (HIIT) can improve cardiometabolic health in individuals with spinal cord injury (SCI). Individuals with SCI experience a ...wide array of barriers to participate in exercise such as lack of time, accessible equipment, and transportation. It is imperative to identify modes of exercise that provide effective health benefits and are accessible while requiring low time commitment. Studies have demonstrated that HIIT has similar positive improvements in cardiometabolic health with 20% of total time commitment compared to moderate intensity exercise (MIT) in short term studies. OBJECTIVES: The purpose of this study is to assess changes in cardiometabolic health following 16-weeks of a home-based telehealth HIIT arm crank exercise program in individuals with long standing SCI. METHODS: Participants were randomly assigned to 16 weeks of HIIT arm crank exercise training or a no-exercise control group. Body composition via DXA, resting energy expenditure (REE), blood lipids, fasting insulin sensitivity, blood pressure, aerobic capacity, and muscular strength and endurance were assessed at baseline and at 16 weeks post intervention. Qualitative interviews were conducted for the HIIT group upon completion of intervention.RESULTS: Five participants (3 male, 2 female; n=3 in control, n=2 in HIIT exercise; mean age 53.5 ± 8.5) with longstanding SCI completed the exercise study. The preliminary data of this study shows significant group by time effects for gynoid % fat (p=0.015) and REE (p=0.006) showing improvement for body composition and REE in the HIIT group relative to control. Although not statistically significant, there were mean improvements in aerobic capacity and muscular endurance in HIIT group compared to control. CONCLUSION: These preliminary data demonstrate that 16 weeks of telehealth HIIT may improve body composition and REE in individuals with SCI. The qualitative results demonstrate that the participants reported enjoying the remote aspect, increases in energy levels, and increases daily quality of life. These preliminary results suggest that a long-term telehealth HIIT program to individuals with SCI and may show improvements in overall health; however, a larger sample size is needed in order to confirm these observations. We hope to demonstrate that home-based telehealth HIIT program will improve cardiometabolic health, can yield high adherence, and be an enjoyable form of exercise for individuals with SCI.
Physical activity (PA) enhances quality of life in older adults, yet few older adults participate in regular PA. Exercise prescriptions are valuable to improve PA among older adults, and fitness ...measures are necessary to develop individualized PA programs. A typical fitness measure is the Senior Fitness Test (SFT) conducted in a supervised setting; however, the acceptability of an unsupervised, self-administered SFT is unknown. The purpose of this study was to assess the acceptability of a home-based self-administered SFT versus a home-based supervised SFT using the Theoretical Framework of Acceptability (TFA). Sixty-five older adults performed select SFT measures in their home on two separate occasions, one supervised and one self-administered. Findings indicated both administration methods was acceptable amongst older adults based on the TFA components. Completing a home-based, self-administered SFT appears to be a viable option for physical fitness testing in older adults.
