Impact of Velcro Cuff Closure on Forearm Skin Temperature In Surfers Wearing a 2mm and 3mm Wetsuit

International Journal of Exercise Science 13(6): 1574-1582, 2020. Surfing is a worldwide sport that often requires participants to wear a wetsuit to assist in thermoregulation. In a recent study, forearm skin temperature decreased by approximately 3 °C while wearing a wetsuit during recreational surfing. The purpose of this study was to test the hypothesis that reducing water flow in and out of the wetsuit by cuffing the wetsuit at the wrist, with a novel cuff closure system (Velcro cuff), would result in greater forearm skin temperature while surfing. One hundred and twelve (94 male, 18 female) recreational surfers between the ages of 18-50 participated in this study. Forearm skin temperature was measured at 1-minute intervals across the surf session in both arms with four wireless iButton thermal sensors located two inches from the styloid process (wrist) and olecranon process (elbow). Following instrumentation, all subjects had one of their wrists randomly cuffed with a one-inch wide Velcro cuff that was tightened to 2 cm less than the circumference of the wrist plus wetsuit. Subjects were then instructed to engage in regular recreational surfing activities for a minimum of 30 minutes at seven beaches in North San Diego County from October to April. No significant differences were found between the average cuffed wrist skin temperature and the average uncuffed wrist skin temperature (p = 0.06). However, average cuffed forearm skin temperature was significantly higher than average uncuffed forearm skin temperature (p = 0.01). Results from this study suggest that cuffing the wrist of wetsuits is a simple technique that can be utilized by surfers to significantly improve forearm skin temperature during surfing. These findings may also have an implication on future wetsuit designs

Characterization of Adult Heart Rate Responses During Recreational Skateboarding at Community Skateparks

International Journal of Exercise Science 13(2): 501-510, 2020. Youth participating in recreational skating at community skate parks attain exercise intensities and durations that are comparable with the CDC’s exercise recommendations for cardiovascular fitness for their age group. However, it is currently unclear if adults who skateboard in the same environment also achieve the recommended intensities and durations for cardiovascular fitness. Therefore, the purpose of this study was to test the hypothesis that skateboarding would elicit heart rates and durations consistent with the CDC’s recommendations for cardiovascular fitness in adults. Fifty-five subjects between ages 18-55 were recruited from six community skateparks for this study. Subjects completed a questionnaire and were instrumented with a Polar V800 heart rate receiver on the left wrist and an H7 Bluetooth heart rate transmitter around the chest below the pectoralis major. Participants were instructed to engage in a typical skateboarding session on their own board with the duration and intensity of activity to be determined by the participant. The mean age of the participants was 27.4 ± 8.5 years, and participants reported skateboarding at a community skate park a mean of 3.1 ± 1.8 days/week. Participants had a mean heart rate of 138.2 ± 21.9 beats per minute (71.7% of age predicted maximum), skated for 65.5 ± 36.2 minutes, and traveled 4.56 ± 4.5 kilometers. Subjects spent 70% of their total duration at moderate-intensity or above and 30% within the low, and below low-intensity range. Results from this study suggest that adults participating in recreational skateboarding in community skateparks achieve the CDC’s exercise recommendations for cardiovascular fitness. These findings may have implications for community skatepark design and professional training programs for adult skateboarding athletes

Sensory Motor Synchronization Data (Fixed Amplitude)

These data were used in preparation of a manuscript for PLOS One

Surf Paddling Data

<p>These data are reported in a manuscript submitted to PLOS One</p

Arnold Tongue Data

These data were used in preparation of a manuscript submitted to PLOS One

Walking on a Vertically Oscillating Platform with Simulated Gait Asymmetry

Asymmetric gait is associated with pain, injury, and reduced stability in patient populations. Data from side by side walking suggest that unintentional synchronization with an external cue may reduce gait asymmetry. Two types of asymmetric gait were examined here: (1) mass imbalance between limbs to simulate single limb amputation and (2) restriction of plantarflexion during toe-off to simulate reduced propulsion from neurological impairment. Twenty-five healthy participants walked normally and with simulated gait asymmetry on a custom-designed treadmill that oscillated in the vertical direction via pneumatic actuation (amplitude: 2 cm, frequency: participant’s preferred step frequency). Swing Time Asymmetry (STA) and Phase Coordination Index (PCI) both increased significantly with the application of unilateral mass and plantarflexion restriction (p &lt; 0.001). However, walking with simulated asymmetry did not alter unintentional synchronization with the treadmill motion. Further, oscillation of the treadmill did not improve STA or PCI while walking with simulated asymmetry. Analysis of synchronized step clusters using the Weibull survival function revealed that synchronization with the platform persisted for longer durations when compared with data from side by side walking. These results suggest that walking on a vertically oscillating surface may not be an effective approach for improving gait asymmetry

Nonlinear Time Series Analysis Of Knee and Ankle Kinematics During Side By Side Treadmill Walking

Nonlinear time series analysis was used to estimate maximal Lyapunov exponents of select ankle and knee kinematics during three different conditions of treadmill walking: independent, side by side, and side by side with forced synchronization of stepping. Stride to stride variability was significantly increased for the condition in which individuals walked side by side and synchronized unintentionally when compared to the conditions of forced synchronization and independent walking. In addition, standard deviations of three kinematic variables of lower extremity movement were significantly increased during the condition in which unintentional synchronization occurred. No relationship was found between standard deviation and estimates of maximal Lyapunov exponents. An increase in kinematic variability during side by side walking for nonimpaired individuals who are not at risk of falling suggests that variability in certain aspects of performance might be indicative of a healthy system. Modeling this variability for an impaired individual to imitate may have beneficial effects on locomotor function. These results may therefore have implications for the rehabilitation of gait in humans by suggesting that a different functional outcome might be achieved by practicing side by side walking as opposed to more commonly used strategies involving independent walking

Fluid Loss in Recreational Surfers

International Journal of Exercise Science 14(6): 423-434, 2021. Surfing offers unique challenges to thermoregulation and hydration. The purpose of this study was to quantify fluid loss in recreational surfers, and to analyze the effects of water temperature, air temperature, exercise intensity, duration, and garment thickness on the total amount of fluid lost during a surf session. A total of 254 male and 52 female recreational surfers were recruited from San Diego, Costa Rica, and Australia to participate in the study. Participants’ hydration status was assessed by comparing nude body mass pre- and post-surf session. Heart rate (HR), used as an index of exercise intensity, was measured throughout the session. Environmental conditions and surf characteristics were recorded. The difference between average pre-mass (73.11 ± 11.88 kg) and average post-mass (72.51 ± 11.78) was statistically significant (0.60 ± 0.55, p \u3c 0.001). Surfers experienced a 0.82 ± 0.73% reduction in body mass. In multivariable linear regression, session duration and body mass index (BMI) were significantly associated with fluid loss. For every 10-minute increase in session duration, there was a 0.06 kg (SE = 0.001; p \u3c 0.001) increase in fluid loss, and for every two unit increase in BMI, fluid loss increased by 0.05 kg (SE = 0.03; p = 0.02). Results suggest that prolonged surfing at high environmental temperatures in participants with high BMI’s resulted in significant body water deficits. Since there is no opportunity to rehydrate during a surf session, surfers must properly pre-hydrate before surfing in order to avoid the detrimental effects of dehydration