Characterizing stress during animal interaction: a focus on the human endocrine response during equine-assisted services

Repeated stresses applied to the rider may contribute to the documented physical and psychosocial outcomes from equine-assisted services. In this brief review, a summary of neuroendocrine markers of stress, including immunoglobulin A, serotonin, cortisol, progesterone, and oxytocin, is presented within the context of the physiology of stress modulation. Results are mixed with regard to the effects of these hormones on rider physiology before, during, and after equine-assisted services. However, some results from existing studies are promising with regard to the attenuation of stress. Future research should include a cross-disciplinary approach when conducting well-controlled studies with proper treatment and experimental fidelity, while also considering exogenous and endogenous factors that influence rider physiology

The Relationship Between Heart Rate Variability and Skeletal Muscle Damage in Female Collegiate Athletes

Heart rate variability (HRV) is an accurate indicator of sympathetic and parasympathetic nervous system activity. With athletes, HRV analysis can be a useful tool in analyzing the readiness to train, recovery status, and chronic adaptations to training, and overtraining. Skeletal muscle damage, which can be an outcome of overtraining, may be assessed using biomarkers in the blood, including creatine kinase (CK). The relationship between skeletal muscle damage and measures of HRV with regards to performance is not known. PURPOSE: The purpose of this study was to determine the relationships between HRV measures and serum CK concentrations. A secondary purpose of this study was to determine what lifestyle factors, other than physical activity levels, may affect HRV measures and serum CK concentrations in the same population. METHODS: Six Female NCAA Division II Volleyball athletes completed the 14-day study. Participants recorded HRV with the use of the Cardiomood smartphone application daily, upon waking, throughout the study. Time domain (i.e., RMSSD) and frequency domain (i.e., low, high, total power) variables were recorded to characterize HRV. Blood samples were collected in an unfasted state at 7 time points throughout the study and analyzed for total CK level (U/L). In addition, a wellness questionnaire completed daily included questions pertaining to fatigue (F), mood (M), stress (ST), soreness (MS), sleep duration (S), sleep quality (SQ), and hydration (H). During structured practice and workout sessions, energy expenditure (EE) was measured using a chest worn monitor. A Pearson product-moment correlation was performed to investigate the relationships among variables with significance set at 0.05. RESULTS: Total CK levels were found to have a significant negative relationship with RMSSD (p = 0.035), and a positive relationship with EE (p \u3c 0.01) and MS (p \u3c 0.01). A significant negative relationship with RMSD and SQ (p = 0.01), and a significant positive relationship with RMSSD and M (p = 0.008) was also found. Within the wellness questionnaire, MS and H had a significant negative relationship (p = 0.021) and M had a significant positive relationship with S (p = 0.038). CONCLUSION: The use of HRV may serve as an accurate monitor of total circulating CK levels in the blood. With regards to the wellness questionnaire, it was found that sleep quality had the largest influence on HRV, reinforcing the importance of sleep and recovery. These results could prove beneficial for coaches in assessing an athlete’s readiness to train and recovery status

Effects of a 500-Mile Backpacking Hike on the Performance of a Competitive Powerlifter

The purpose of this study was to evaluate the effects of a long-distance backpacking trip and a high protein diet on body composition, strength, power, and aerobic performance. A single participant (male, aged 29 years) hiked 34 days on the Colorado Trail. Dependent variables were assessed pre-hike and post-hike and included body mass, body fat percentage, bone mineral density, maximum oxygen consumption (VO2max), resting metabolic rate (RMR), total cholesterol, triglycerides, high density lipoprotein (HDL), low density lipoprotein (LDL). Cardiovascular dependent variables included resting heart rate, systolic blood pressure (SBP) and diastolic blood pressure (DBP). Other performance outcomes included strength in squat, bench press, and deadlift, and vertical leap. Resting heart rate and a journal documenting a breakdown of calories expended and calories consumed were recorded daily while on the hike. The average daily duration of a hike was 8:43 ± 1:45 hours. The participant’s mass decreased by 2.5 kg (4% of body weight), body fat decreased by 1.2%, RMR decreased by 5 kcal/day, and VO2max increased by 8.7 mL/kg/min (17%). Among metabolic variables, total cholesterol increased by 18 mg/dL (10%); triglyceride concentration decreased by 23 mg/dL (29%); HDL decreased by 1 mg/dL (2%), and; LDL increased by 24 mg/dL (23%). With regard to cardiovascular variables, resting heart rate decreased from 85 bpm to 67 bpm (21%), SBP decreased by 39 mmHg (27%), and DBP decreased by 2 mmHg (3%). Among performance variables, maximal squat performance decreased by 29.5 kg (19%), maximal bench press performance decreased by 18.2 kg (16%), maximal deadlift decreased 31.7 kg (17%), and vertical jump distance decreased 13 cm (14%). The average daily dietary variables were as follows: average calories consumed = 4000 ± 463 kcal/day; average calories expended from hiking and metabolic rate combined = 5188 ±1197 kcal/day; average daily caloric deficit = -1165 ± 1070 kcal/day; average carbohydrate intake = 501 ± 78 g/day; average protein intake = 143 ± 19 g/day; average fat intake = 154 ± 25g/day. The magnitude and duration of an extended backpacking trip can lead to a reduction in strength and power. A diet high in protein did not prevent the loss of lean body mass

Comparison Of Cognitive Performance Following One Hour Of Passive Heating Or Walking In Older Adults: A Preliminary Analysis

Moderate-intensity exercise increases measures of cognitive performance such as working memory and cognitive flexibility. Hyperthermia can result in declines in cognitive performance through reduced motor function and response inhibition. However, these results have been observed during cognitive performance in the heat while core temperatures remain elevated. Heat therapy may promote improvements in cognitive function after treatment similar to exercise training by inducing a stress-related response. The purpose of this study was to compare cognitive performance immediately following one hour of moderate-intensity aerobic exercise or one hour of whole-body passive heating. METHODS: Four adults (age: 67.3 + 3.3 years, BMI: 29.0 + 5.4 kg/m2, 2 female) participated in a randomized repeated measures study. Participants completed either one hour of moderate intensity walking on a treadmill (TM; 65-75% age-predicted maximum heart rate) or one hour of seated passive heating (HEAT) in a controlled environmental heat chamber (32-35 degrees Celsius, \u3c 40% humidity). Cognitive performance was measured using computerized software (Automated Neuropsychological Assessment Metrics, ANAM, Vista LifeSciences, Inc.), which provides objective measures of cognitive performance through a variety of test batteries designed to measure variables such as motor coordination, cognitive flexibility, and response inhibition. Variables were analyzed as a change in score from the familiarization exam (pre- or post-treatment minus – baseline) to minimize the learning effect. RESULTS: No differences between measures of motor coordination (TM: 6 + 12.7 vs. 5 + 12.7; HEAT: 0 + 1.4 vs. -1 + 1.4), cognitive flexibility (TM: -1 + 1.4 vs. 1.5 + 0.7; HEAT: 3.5 + 0.7 vs. 3.5 + 0.7), or response inhibition (TM: 17 + 22.6 vs. 23.5 + 23.3; HEAT: 1.5 + 2.1 vs. 8 + 2.8) were found following either treatment. CONCLUSION: One bout of moderate intensity aerobic exercise or whole-body passive heating does not impair cognitive performance. In addition, one hour of passive heating does not result in decreased cognitive performance in older adults. Post-hyperthermic stress response did not impair cognitive function

The Relationship of Physiological and Fitness Variables to Performance in CrossFit®-based Exercise: Preliminary Findings

CrossFit® is a rapidly expanding exercise program as well as an emerging competitive sport. Little is known regarding the correlation of physical fitness measures and performance in CrossFit®-based events. PURPOSE: The purpose of this study was to determine the relationship between various physiological and fitness variables and performance in a typical CrossFit®-based workout. METHODS: Nine male participants (age = 32.2 ± 3.6 yrs; height = 173.1 ± 9.8 cm; weight = 86.1 ± 11.6 kg; BMI = 28.6 ± 1.2 kg/m2) who had performed CrossFit® as their primary exercise program at least 3 days/week for the past 12 months were recruited. Participants performed a test of maximal aerobic fitness (VO2max), a Wingate test, a DEXA scan, a 1RM Clean and Jerk, and a series of exercises that would typically be included in a CrossFit®-based workout. More specifically, participants performed 15 Wall Ball exercises (20 lbs.), 15 Box Jumps (24 in.), 10 Burpees over a barbell, and 10 Kipping Pullups. If all exercises were completed, the participants repeated the exercises in the same order. The participants were asked to stop after 12 min, and the total number of repetitions completed was recorded. Questions regarding the participants’ exercise history and dietary habits were asked. Spearman’s correlation was used to identify relationships between the variables and performance (number of repetitions completed) during the CrossFit®-based workout. Participants were also grouped into “high” (≥ median) or “low” (\u3c median) groups, and independent samples t-tests were used to compare how each group performed during the CrossFit®-based workout. Statistical significance was set at .05. RESULTS: Performance during the CrossFit®-based workout had strong, positive relationships with strength-to-body weight ratio (r = .686; p = .041), 1RM Clean and Jerk (r = .915; p = .001), and years of experience (r = .869; p = .002). Participants with higher strength-to-body weight ratios (p = .036), lower fatigue index (p = .022), lower body fat percentage (p = .022), higher weight lifted during the 1RM Clean and Jerk (p = .017), and more years of experience (p = .027) completed more repetitions during the CrossFit®-based workout. Significance was not found with any other variable. CONCLUSION: Based on these early findings, anaerobic fatigue resistance, body fat percentage, muscular power, and exercise history appear to be significant predictors of performance in CrossFit®-based workouts

Pressurized Device for Mitigating Atrophy in Soleus During Long-Duration Spaceflight

A major concern with long duration spaceflight, skeletal muscle atrophy is most detrimental in lower limb musculature, particularly in muscles critical for proper gait, such as the soleus. The decline of muscle activation and the suppression of sensory input from plantar sole mechanoreceptors can add to the attenuation of skeletal muscle health during spaceflight. More specifically, inhibition of sensory input from sole receptors, such as with gravitational unloading, decreases selective activation, thereby negatively affecting muscle tone and inevitably resulting in lower limb atrophy. PURPOSE: To design, fabricate, and test a specialized boot with an insole that applies oscillating pneumatic pressure for set periods of time to augment neuromuscular activation of the soleus through the plantar sole\u27s mechanoreceptors, which may minimize atrophy of lower extremity muscles. METHODS: The custom boot was originally designed in three-dimensional modeling software (Solidworks Premium, Waltham, MA). Components of the boot included: a lightweight medical walking brace, Metro-ATmega circuit board, air pump and vacuum DC motor, force resistive sensor, and kPa sensor. The boot was programmed using C++ to allow the user to wear the boot for 20 minutes (oscillating continuously) at the start of every hour with an automatic timer for 6 hours per day. Surface electromyography (EMG) measured electrical activity in lower extremity muscles while wearing the boot. The location of all electrodes were determined according to the SENIAM project (Surface Electromyography for the Non-Invasive Assessment of Muscles): 1) for soleus, electrode placed at two-thirds of the line between the medial condyle of the femur to the medial malleolus; 2) for medial head of the gastrocnemius, electrode placed at one-third of the line between the head of the fibula and the heel; 3) for ground, electrode placed at the tibial tuberosity. Muscle activation of the gastrocnemius was measured to investigate any co-activation of nearby musculature on the posterior leg. RESULTS: Upon airbag inflation, the soleus exhibited the greatest amplitude (30 to 50 µV versus 5 to 15 µV) when the ankle attempted to plantarflex while maintaining a neutral position. When the airbags are inflated, the pressure output corresponds to approximately 111 kPa. When the airbags are deflated, the pressure output corresponds to approximately 66 kPa, creating a pressure difference of 45 kPa. During the 20 min runtime, the airbags take 3.3 sec to inflate and 3.0 sec to deflate, creating the oscillating effect. When fully charged, the battery can sustain one full, 6-hour session with each lasting 20 minutes. CONCLUSION: Pneumatic pressure integrated into a customized therapeutic walking boot may elicit neuromuscular activity in the lower extremity musculature, which indicates that the device may help in attenuating the negative neuromuscular adaptations in the soleus via afferent signaling

Training Manipulations Based on Acute Heart Rate Variability Measures

Heart rate variability (HRV) is an accurate indicator of sympathetic and parasympathetic nervous system activity. The balance between these systems affects the time between heartbeats. A high variability between heartbeats is equated to a greater influence from the parasympathetic nervous system. In this state, an individual is well rested, and therefore possesses higher readiness to perform physical activity. Through the use of smartphone applications (apps), athletes and coaches can collect accurate short-term HRV readings to assess autonomic nervous system balance. These apps provide a readiness to train score that may prove beneficial in adjusting daily training loads to maximize performance. PURPOSE: The purpose of this study is to characterize the changes in lower-body strength and power before and after a 6-week strength training program while manipulating intensity based on daily HRV readiness measures in female collegiate softball athletes. METHODS: Nine female NCAA Division II Softball athletes completed the 6-week training protocol. Participants were split into an experimental group (E; n = 5; age = 20.5±0.7 yrs, height = 166.9±2.7 cm, weight = 59.9±7.6 kg), who completed the training with the intensity adjusted based off of daily HRV readiness scores, and a control group (C; n = 4; age = 20.6±0.8 yrs, height = 171.7±1.2 cm, weight = 70.7±30.3 kg), who completed the training with no changes in exercise intensity. Measures of HRV were taken prior to each training session and used to calculate readiness scores with the use of a smartphone app. Participants completed 3 strength-training sessions per week throughout the study. Lower-body strength and power measurements were assessed before and after the protocol. One-repetition maximums on the back squat (SQ) and clean (CL) exercises and maximum vertical jump (VJ) height were collected. RESULTS: Lower-body power measurements were increased in the E group (CL: 51.3 vs. 56.9 kg, p = 0.047; VJ: 40.1 vs. 44.7 cm, p = 0.037) and the C group (CL: 56.8 vs. 63.6 kg, p = 0.021; VJ: 41.6 vs. 46.2 cm, p = 0.034), following 6 weeks of strength training. No significant differences were observed in lower body strength measurements in the E group (SQ: 74 vs. 84.1kg, p = 0.21) or the C group (SQ: 75.5 vs. 86.6 kg, p = 0.2). Significant differences were found between the prescribed volume of training and the completed volume of training (25364 vs 21650 kg, p = 0.014) in the E group. No significant differences (p \u3e 0.05) were found with SQ, CL, and VJ measures between the E and C groups following 6 weeks of strength training. No significant differences (p \u3e 0.05) were found in daily HRV measures between the E and C groups. CONCLUSION: Both groups exhibited similar HRV scores throughout the 6-week training protocol. Using daily short-term HRV readings, training intensity can be reduced without leading to any differences in lower-body strength and power improvements in female collegiate softball athletes

Anaerobic Performance in Female Collegiate Wrestlers During Ovulation Versus the Mid-luteal Phase of the Menstrual Cycle: A Pilot Study

Anaerobic performance may vary during different phases of the menstrual cycle. The greatest differences occur between the late-follicular phase (i.e., ovulation) and the mid-luteal phase. Optimal anaerobic performance may be observed during the mid-luteal phase. PURPOSE: To explore differences in upper and lower body anaerobic performance during ovulation versus the mid-luteal phase of the menstrual cycle in collegiate female wrestlers. METHODS: Six female collegiate wrestlers (age = 18.6 ± 0.2 yrs; height = 165.0 ± 0.5 cm; body mass = 79.7 ± 9.6 kg; lean body mass = 45.6 ± 2.8 kg; % body fat = 31.4 ± 6.6%) performed both upper and lower body Wingate tests, each lasting 30 seconds, during the ovulation and the mid-luteal phases of the menstrual cycle. Upper and lower body tests were performed 24 hours apart. Menstrual cycle phases were determined by calendar tracking, reverse estimation of ovulation, and administration of a urinary luteinizing hormone test assessed daily until positive results indicated ovulation. Lower body power was measured using a Velotron cycle ergometer, with a resistance of 0.075 kg/kg applied after a 5-second sprint at a resistance of 1 kg (50 W). Peak power (W) and relative power (W/kg) were measured. Upper body power was measured using a Monark hand ergometer with a 0.045 kg/kg resistance applied after a 5-second sprint at a resistance of 0.5 kg (25 W). Peak power (W) and relative power (W/kg) was calculated using rotation count, weight applied, and distance per rotation. Paired t-tests were used to analyze differences in means during the ovulation vs mid-luteal phases with a significance level of 0.05. RESULTS: There were no significant differences between trials for any variables measured. Lower body peak power (W) was 848.3 ± 126.1W vs 855.0 ± 143.9W. Lower body relative power (W/kg) was 11.8 ± 0.7W/kg vs 11.9 ± 0.8W/kg. Upper body peak power (W) was 162.1 ± 29.6 vs 160.2 ± 13.2W. Upper body relative power (W/kg) was 2.3 ± 0.4W/kg vs 2.2 ± 0.2W/kg. CONCLUSION: There may not be an optimal timing of significantly increased anaerobic performance in regard to menstrual phase in these wrestlers

The Effects of Equine-Assisted Therapy on Gait in Adults with Parkinson’s Disease: A Preliminary Analysis

Parkinson’s disease (PD) is a chronic, progressive, neurological disorder caused by the destruction of dopamine-producing neurons in the substantia nigra of the brain. To treat motor symptoms of PD, individuals may choose alternative modes of exercise, such as equine-assisted therapy (EAT), to improve physiological health. PURPOSE: To determine changes in gait following 8 weeks of Equine Assisted Therapy (EAT) in older men with PD. METHODS: Six older adults (age = 68.0 ± 8.6 yrs; height = 178.6 ± 8.3 cm; weight = 93.4 ± 16.3 kg; Hoehn and Yahr classification = 2.8 ± 0.4; time since diagnosis = 7.3 ± 5.0 yrs) performed two, 60-minute riding sessions weekly for 8 weeks. Before, midway, immediately after, and at two points following the EAT program (at 8 weeks and 16 weeks), spatiotemporal parameters of gait were measured using motion capture with infrared markers strategically placed on lower-body anatomical landmarks. Participants walked at a self-selected speed without the use of an assistive device in the capture space for 15 consecutive strides, turned around, and walked back across the space. Gait velocity, step length, time spent in stance phase, time spent in swing phase, toe clearance were collected. Data were analyzed using a repeated-measures analysis-of-variance and a Bonferroni correction with a significance level of 0.05. RESULTS: Gait velocity (101.8 ± 29.1 vs. 109.2 ± 34.9 vs. 116.3 ± 32.8 vs. 105.7 ± 26.2 vs. 108.0 ± 25.4 cm/s for pre-EAT, midway through EAT, immediately post-EAT, 8 weeks after EAT concluded, and 16 weeks after EAT concluded, respectively) was significant across all time points (p = 0.03). All other variables were statistically similar (p \u3e 0.05) across all time points. CONCLUSION: There is an observable trend towards significance in each gait variable immediately after 8 weeks of EAT. The study is ongoing and will further explore these differences

Cardiorespiratory and biomechanical responses to simulated horseback riding in healthy children

TACSM Abstract Cardiorespiratory and biomechanical responses to simulated horseback riding in healthy children B RHETT RIGBY, ZACHARIAS PAPADAKIS, ANNIE A BANE, JIN K PARK, and PETER W GRANDJEAN Baylor Laboratories for Exercise Science and Technology; Department of Health, Human Performance, and Recreation; Baylor University; Waco, TX Category: Doctoral ABSTRACT The movement of specific body segments during horseback riding is similar to common physical activities such as walking. Yet, little is known regarding the cardiovascular responses to horseback riding (HBR) which may be due to how difficult it is to quantify the physical work of HBR. The purpose of this study was to characterize cardiorespiratory and pelvic kinematic responses to simulated horseback riding (SHR) in apparently healthy children. These responses were compared to walking on a treadmill at different intensities. Fifteen healthy children (8 females, 7 males; 9+3 years of age; height 56+6 in; weight 92.0+41.0 lb; body fat 27+8%) walked at steady state on a treadmill (1-3 mph in 0.5 mph increments, 0% grade) during one session and completed SHR [low intensity (0.27 Hz) and high intensity (0.65 Hz)] during three sessions on differnet occasions. Physiologic variables, such as HR, VO2, VE, SBP, DBP, were measured at rest and steady-state exercise at each intensity. Mean arterial pressure (MAP) and rate pressure product (RPP) were calculated. Pelvic kinematics were measured in a similar manner during SHR. Physiological variables across all three SHR sessions were similar at each intensity (p\u3e0.05). VO2, VE, MAP and RPP were greater with high-intensity riding compared to low-intensity riding and rest. Pelvic kinematics followed the same pattern and were reproducible across SHR sessions. Treadmill walking at all speeds elicited greater magnitudes in the physiological variables compared to SHR. The ICC for RPP, an important variable used to index cardiorespiratory fitness, was 0.057 indicating good reproducibility across SHR sessions. The results of the present study suggest that cardiorespiratory responses and pelvic kinematics are reproducible with SHR in young children and these responses were lower than those elicited by treadmill walking at 1 mph. Table 1: Means of cardiorespiratory variables at rest and during simulated horseback riding Variable Rest Low Intensity Riding High Intensity Riding Absolute VO2 (ml/min) 0.219 0.236 0.284 (p\u3c0.0001) Relative VO2 (ml/kg/min) 5.712 6.095 7.035 (p\u3c0.0001) VE (L/min) 7.744 8.340 9.898 (p\u3c0.0001) MAP (mmHg) 75.225 75.783 77.488 (p\u3c0.0002) RPP 96.072 96.742 102.736 (p\u3c0.0001