Chronotropic Incompetence During Exercise Testing as a Marker of Autonomic Dysfunction in Individuals with Early Parkinson's Disease.

BACKGROUND: An attenuated heart rate response to exercise, termed chronotropic incompetence, has been reported in Parkinson's disease (PD). Chronotropic incompetence may be a marker of autonomic dysfunction and a cause of exercise intolerance in early stages of PD. OBJECTIVE: To investigate the relationship between chronotropic incompetence, orthostatic blood pressure change (supine - standing), and exercise performance (maximal oxygen consumption, VO2peak) in individuals with early PD within 5 years of diagnosis not on dopaminergic medications. METHODS: We performed secondary analyses of heart rate and blood pressure data from the Study in Parkinson's Disease of Exercise (SPARX). RESULTS: 128 individuals were enrolled into SPARX (63.7±9.3 years; 57.0% male, 0.4 years since diagnosis [median]). 103 individuals were not taking chronotropic medications, of which 90 had a normal maximal heart rate response to exercise testing (155.3±14.0 bpm; PDnon-chrono) and 13 showed evidence of chronotropic incompetence (121.3±11.3 bpm; PDchrono, p < 0.05). PDchrono had decreased VO2peak compared to PDnon-chrono (19.7±4.5 mL/kg/min and 24.3±5.8 mL/kg/min, respectively, p = 0.027). There was a positive correlation between peak heart rate during exercise and the change in systolic blood pressure from supine to standing (r = 0.365, p < 0.001). CONCLUSIONS: A subgroup of individuals with early PD not on dopaminergic medication had chronotropic incompetence and decreased VO2peak, which may be related to autonomic dysfunction. Evaluation of both heart rate responses to incremental exercise and orthostatic vital signs may serve as biomarkers of early autonomic impairment and guide treatment. Further studies should investigate whether cardiovascular autonomic dysfunction affects the ability to exercise and whether exercise training improves autonomic dysfunction.

Study in Parkinson's disease of exercise phase 3 (SPARX3): study protocol for a randomized controlled trial.

BACKGROUND: To date, no medication has slowed the progression of Parkinson's disease (PD). Preclinical, epidemiological, and experimental data on humans all support many benefits of endurance exercise among persons with PD. The key question is whether there is a definitive additional benefit of exercising at high intensity, in terms of slowing disease progression, beyond the well-documented benefit of endurance training on a treadmill for fitness, gait, and functional mobility. This study will determine the efficacy of high-intensity endurance exercise as first-line therapy for persons diagnosed with PD within 3 years, and untreated with symptomatic therapy at baseline. METHODS: This is a multicenter, randomized, evaluator-blinded study of endurance exercise training. The exercise intervention will be delivered by treadmill at 2 doses over 18 months: moderate intensity (4 days/week for 30 min per session at 60-65% maximum heart rate) and high intensity (4 days/week for 30 min per session at 80-85% maximum heart rate). We will randomize 370 participants and follow them at multiple time points for 24 months. The primary outcome is the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) motor score (Part III) with the primary analysis assessing the change in MDS-UPDRS motor score (Part III) over 12 months, or until initiation of symptomatic antiparkinsonian treatment if before 12 months. Secondary outcomes are striatal dopamine transporter binding, 6-min walk distance, number of daily steps, cognitive function, physical fitness, quality of life, time to initiate dopaminergic medication, circulating levels of C-reactive protein (CRP), and brain-derived neurotrophic factor (BDNF). Tertiary outcomes are walking stride length and turning velocity. DISCUSSION: SPARX3 is a Phase 3 clinical trial designed to determine the efficacy of high-intensity, endurance treadmill exercise to slow the progression of PD as measured by the MDS-UPDRS motor score. Establishing whether high-intensity endurance treadmill exercise can slow the progression of PD would mark a significant breakthrough in treating PD. It would have a meaningful impact on the quality of life of people with PD, their caregivers and public health. TRIAL REGISTRATION: ClinicalTrials.gov NCT04284436 . Registered on February 25, 2020.

Relationship Between the 20-m Multistage Fitness Test and 2.4-km Run in Law Enforcement Recruits.

ABSTRACT: Lockie, RG, Dawes, JJ, Moreno, MR, Cesario, KA, Balfany, K, Stierli, M, Dulla, JM, and Orr, RM. Relationship between the 20-m multistage fitness test and 2.4-km run in law enforcement recruits. J Strength Cond Res 35(10): 2756-2761, 2021-In the United States, the 2.4-km run is arguably the most common law enforcement aerobic assessment. Potential limitations are that recruits use an internal pacing strategy, the test requires fewer direction changes, and less-fit recruits run for longer. The 20-m multistage fitness test (20MSFT) is commonly used internationally to assess aerobic fitness in law enforcement recruits and provides an external pacing strategy. This study documented sex differences between the 2.4-km run and 20MSFT in law enforcement recruits, and between-test relationships. Retrospective analysis on 8 academy classes (463 men and 87 women) from 1 agency was conducted. The 20MSFT was completed before academy and the 2.4-km run in the first week. Between-sex comparisons in the 2.4-km run and 20MSFT were conducted with independent-samples t-tests and effect sizes. Estimated V̇o2max from the tests was compared with paired-samples t-tests. Correlations and linear regression calculated 2.4-km run and 20MSFT relationships. There were significant between-sex differences for the 2.4-km run and 20MSFT (p < 0.01), with moderate (d = 0.9) and small (d = 0.4) effects, respectively. Estimated 2.4-km run V̇o2max was greater than that from the 20MSFT (p < 0.01). The 2.4-km run had significant relationships with the 20MSFT (r = -0.6), although the regression equations were low (r2 = 0.30-0.37). Between-sex differences in the 20MSFT seemed less than for those in the 2.4-km run. Nonetheless, even with significant relationships between the tests, the 20MSFT induces a higher running intensity and direction changes. This may limit transferability with the 2.4-km run in law enforcement recruits.

Analyzing the Training Load Demands, and Influence of Sex and Body Mass, on the Tactical Task of a Casualty Drag via Surface Electromyography Wearable Technology.

This study measured the training load (TL) demands associated with a military-specific casualty drag measured via surface electromyography (sEMG) wearable technology, and the influence of sex and body mass on these measures. Thirty-six college-aged participants (males = 25; females = 11) performed two trials of a 123-kg (91-kg dummy with 32-kg load) backwards casualty drag over 15 m. Time was recorded to calculate drag velocity, with the fastest trial analyzed. Prior to testing, participants were fitted with compression garments embedded with sensors to measure the vastus lateralis and medialis (quadriceps; QUAD), biceps femoris (BF), and gluteus maximus (GM) of both legs. The sEMG signal for each muscle was measured as a percentage of maximal voluntary contraction to calculate TL. The variables included TL (total, QUAD, BF, GM), and between-muscle ratios. The sample was also ranked and median split via body mass into heavier and lighter groups. Independent samples t-tests calculated differences between drag velocity and TL for the sex and body mass groups. Pearson's correlations calculated relationships between body mass and velocity with the TL variables (combined, males, females). Females and lighter participants experienced greater TL compared to males and heavier participants, respectively (p < 0.01). A slower drag velocity correlated with a greater total and QUAD TL for all participants, males, and females (p ≤ 0.03, r = -0.65-0.80). Performing a slower casualty drag will increase TL demands, predominantly via QUAD stress. Training staff should develop the muscles important for the drag, especially for females and lighter males.

The Effects of Lateral Bounds on Post-Activation Potentiation of Change-of-Direction Speed Measured by the 505 Test in College-Aged Men and Women.

Forty recreationally-trained individuals completed four testing sessions to determine whether lateral bounds (LB) or weighted lateral bounds enhanced change-of-direction (COD) speed measured by the 505 COD speed test. Session 1 included vertical jump and lateral bound (LB) testing to measure power. Sessions 2-4 involved three randomized conditioning activities (CA): 3 × 5 LB; 3 × 5 weighted LB (10% body mass provided by a weighted vest); and a control condition (4-min rest). The 505 COD speed test was performed 5- and 2.5-min pre-CA, and ~15 s, 4, 8, 12, and 16 min post-CA. A 3 × 6 repeated measures analysis of variance (ANOVA) calculated performance changes across time points post-CA. A 3 × 2 repeated measures ANOVA analyzed best potentiated performance. Smallest worthwhile change (SWC) measured within-subject 505 COD speed test performance. Partial correlations controlling for sex calculated relationships between the vertical jump, LB, and percent potentiation. There were no differences (p = 0.919) in 505 time relative to baseline for any CA, nor was the SWC exceeded. The best potentiated 505 time was faster (p < 0.001) than baseline for all CA, with no between-CA differences. There were no significant (p = 0.056-0.993) correlations between power and potentiation. LB and weighted LB did not potentiate the 505 COD speed test, although performance was not hindered.

A Preliminary Analysis of Relationships Between a 1RM Hexagonal Bar Load and Peak Power with the Tactical Task of a Body Drag.

A critical job task for law enforcement officers that should be influenced by strength is the body drag. This study analyzed relationships between absolute and relative strength measured by a one-repetition maximum hexagonal bar deadlift (1RM HBD), with body drags completed with 74.84 kg and 90.72 kg dummies. Twenty recreationally-trained individuals completed the 1RM HBD in one session, with peak power measured via a linear position transducer. Over two subsequent sessions, participants dragged the 74.84 kg and 90.72 kg dummies with two techniques. The first technique followed Californian standards, where participants wrapped their arms around the dummy and lifted it to standing before timing commenced. In the adapted technique, timing included the initial manipulation of the dummy. Participants dragged the dummy as quickly as possible over a 9.75 m distance. Partial correlations and linear regression (controlling for sex; p < 0.05) analyzed relationships between the HBD and body drags. The standard 74.84 kg body drag correlated with every HBD variable (r = -0.477 to -0.666), and was predicted by the absolute 1RM HBD (r2 = 0.467). The adapted 74.84 kg drag correlated with all HBD variables (r = -0.535 to - 0.754), and was predicted by peak power and the 1RM HBD (r2 = 0.758). Both 90.72 kg drags correlated with absolute and relative 1RM HBD (r = -0.517 to -0.670). Strength related to all body drags; peak power may be more important for drags with lighter loads. Strength training should be a focus in law enforcement to enhance drag performance.

The Influence of Physical Fitness on Reasons for Academy Separation in Law Enforcement Recruits.

This study analyzed the effects physical fitness may have on reasons for academy separation in law enforcement recruits. A retrospective analysis was conducted on 401 recruits; 330 recruits graduated (GRAD), and 71 recruits separated at various times during academy. Twenty-eight recruits separated for personal reasons (SEPPR); 18 due to physical training failures (i.e., poor fitness) or injury (SEPFI); and 25 due to academic or scenario failures (SEPAS). Fitness testing occurred prior to academy, and included: Push-ups and sit-ups in 60s; a 75-yard pursuit run (75PR); vertical jump; medicine ball throw; and multistage fitness test (MSFT). A one-way ANOVA with Bonferroni post hoc compared between-group fitness test performance. A multiple stepwise regression calculated whether recruit characteristics or fitness could predict separation. The GRAD group was younger than the SEPAS group (p < 0.01), faster in the 75PR than the SEPFI group (p = 0.02), and completed more MSFT shuttles than the SEPPR and SEPFI groups (p = 0.01). Age predicted GRAD and SEPAS group inclusion; MSFT predicted GRAD, SEPPR, and SEPFI group inclusion. Recruits who had superior high-intensity running capacity (75PR) and aerobic fitness (MSFT) should have a better chance of completing academy. However, this could be influenced by training practices adopted during academy.

Physical Fitness Characteristics That Relate to Work Sample Test Battery Performance in Law Enforcement Recruits.

This study determined relationships between an agency-specific fitness test battery (PT500), and a work sample test battery (WSTB) in law enforcement recruits. Retrospective analysis on 219 males and 34 females from one agency was conducted. The PT500 comprised: push-ups, sit-ups, and mountain climbers in 120 s; pull-ups; and 201 m and 2.4 km runs. The WSTB comprised: 99 yard (90.53 m) obstacle course (99OC); body drag (BD) with a 165 pound (75 kg) dummy; 6 foot (1.83 m) chain link fence (CLF) and solid wall (SW) climb; and 500 yard (457.2 m) run (500R). Partial correlations, controlling for sex, calculated PT500 and WSTB relationships (p < 0.05). Stepwise regression determined whether fitness predicted WSTB performance. The 500R related to all PT500 assessments (r range = -0.127⁻0.574), 99OC related to all bar push-ups and mountain climbers, and BD related to none. The CLF related to sit-ups, pull-ups, and 2.4 km run; SW related to mountain climbers, pull-ups, and 2.4 km run (r range = -0.127⁻-0.315). Push-ups, pull-ups, and 2.4 km run were involved in predictive relationships for 99OC, CLF, SW, and 500R (r² range = 0.217⁻0.500). To perform better in the WSTB and job-specific tasks, developing upper-body strength and aerobic fitness may be beneficial.

Validity and Reliability of Surface Electromyography Measurements from a Wearable Athlete Performance System.

The Athos ® wearable system integrates surface electromyography (sEMG ) electrodes into the construction of compression athletic apparel. The Athos system reduces the complexity and increases the portability of collecting EMG data and provides processed data to the end user. The objective of the study was to determine the reliability and validity of Athos as compared with a research grade sEMG system. Twelve healthy subjects performed 7 trials on separate days (1 baseline trial and 6 repeated trials). In each trial subjects wore the wearable sEMG system and had a research grade sEMG system's electrodes placed just distal on the same muscle, as close as possible to the wearable system's electrodes. The muscles tested were the vastus lateralis (VL), vastus medialis (VM), and biceps femoris (BF). All testing was done on an isokinetic dynamometer. Baseline testing involved performing isometric 1 repetition maximum tests for the knee extensors and flexors and three repetitions of concentric-concentric knee flexion and extension at MVC for each testing speed: 60, 180, and 300 deg/sec. Repeated trials 2-7 each comprised 9 sets where each set included three repetitions of concentric-concentric knee flexion-extension. Each repeated trial (2-7) comprised one set at each speed and percent MVC (50%, 75%, 100%) combination. The wearable system and research grade sEMG data were processed using the same methods and aligned in time. The amplitude metrics calculated from the sEMG for each repetition were the peak amplitude, sum of the linear envelope, and 95th percentile. Validity results comprise two main findings. First, there is not a significant effect of system (Athos or research grade system) on the repetition amplitude metrics (95%, peak, or sum). Second, the relationship between torque and sEMG is not significantly different between Athos and the research grade system. For reliability testing, the variation across trials and averaged across speeds was 0.8%, 7.3%, and 0.2% higher for Athos from BF, VL and VM, respectively. Also, using the standard deviation of the MVC normalized repetition amplitude, the research grade system showed 10.7% variability while Athos showed 12%. The wearable technology (Athos) provides sEMG measures that are consistent with controlled, research grade technologies and data collection procedures.