Effect of robotic gait training on muscle and bone characteristics in spinal cord transected rats.

Osteoporosis and loss of muscle mass are secondary issues with spinal cord injury. Robotic gait training has provided evidence of increasing bone density and muscle mass, but its effect on bone strength is undetermined. The purpose of this study was to determine the effect of a 6-week robotic locomotion training program on skeletal muscle mass and bone characteristics. Twelve female Sprague-Dawley rats received a mid-thoracic spinal cord transection at 5 days old and at 3 weeks old were assigned to a Control or Trained Group. The Trained Group performed 5-min sessions on the Rat Stepper 5 days a week for 6 weeks with 90% of body weight supported. At the end of the 6 weeks, body mass was obtained and right femurs and four lower extremity muscles were harvested. Femur bone mineral density was measured with DXA and mechanical characteristics of the femur were determined via 3-point bending testing. Independent t-tests, effects sizes and percent differences were computed between the two groups (p < 0.05). The Trained Group had significantly larger normalized femur mass (p = 0.007) and normalized soleus muscle mass (p = 0.033) when compared to the Control Group. There was a medium or large effect size with the Trained Groups' femurs having larger mass, bone mineral density, rupture loads, cortical wall thickness, shaft cross sectional area, soleus mass, normalized gastrocnemius mass, and smaller shaft inner diameters compared to the Control Group. These changes may contribute to decreasing osteoporosis and fracture risk in those with spinal cord injuries.

Heart Rate Response and Locomotor Activity of Female Skateboarders, BIPOC Skateboarders, and Non-skateboard Users During a Typical Session at a Community Skatepark.

Prior research has demonstrated that male adults and youth engaged in skateboarding at community skateparks achieve heart rates that meet or exceed recommendations for exercise by the CDC. However, these studies do not adequately evaluate other non-traditional or ethnically diverse users who may differ in how they utilize the skatepark and in their cardiovascular response. The purpose of this experiment was to measure heart rate response and locomotor movement in three lesser studied groups that frequently utilize community skateparks, and to compare these results with those reported previously in male adult and youth skateboarders. Fifty-six skatepark users were analyzed, including thirty female and BIPOC skateboarders, and twenty-six non-skateboard users. All participants were instrumented with a HR monitor with GPS capability and asked to engage in their preferred activity with no duration specified. Average heart rate and time spent at high and moderate levels of heart rate intensity were not statistically different among the groups studied here, nor were they different from those reported previously for male adult and youth skateboarders. Distances traveled, average, and peak velocities were also not statistically different among the groups studied here, but all were significantly lower than values previously reported for adult male skateboarders. While some differences in distances traveled and velocity were noted, all groups met or exceeded CDC guidelines for cardiovascular fitness. These data suggest that skateparks can help a community achieve health outcomes, particularly among diverse users.

The characterization of thermal perception in recreational surfers wearing wetsuits.

The purpose of this study was to characterize the perception of heat loss, comfort, and wetness in recreational surfers wearing wetsuits, to compare these data with changes in skin temperature reported in prior studies, and to examine the impact of wetsuit thickness, zipper location, and accessory use on thermal sensation and comfort. Following their surf session, nine-hundred and three male (n = 735) and female (n = 168) recreational surfers responded to a series of questions regarding thermal comfort/sensation, wetsuit characteristics, and surfing history. Average whole body thermal sensation rating was 0.8 ± 3.6 on a scale of -10 to +10 and average whole body thermal comfort rating was 1.5 ± 1.2, midway between "just comfortable" and "comfortable." Overall, surfers felt coldest in their feet, hands, and head. Under their wetsuits, surfers felt the coldest, wettest, and least comfortable in their chest, lower legs, lower arms, and upper back. Wetsuit accessory use had the greatest impact on regions identified as coldest, least comfortable, and wettest. These data suggest that wetsuit design should focus on optimizing water access points and improving accessories for the feet, hands, and head.

Heart Rate Response, Duration, Grip Strength, and Anthropometric Characteristics in Recreational Indoor Rock Climbers.

ABSTRACT: Smetanka, RG, Armenta, RF, Nessler, JA, and Newcomer, SC. Heart rate response, duration, grip strength, and anthropometric characteristics in recreational indoor rock climbers. J Strength Cond Res 36(3): 832-837, 2022-Despite the growing popularity of recreational indoor rock climbing, there is a lack of research on cardiovascular responses to rock climbing. In addition, although the importance of body composition and grip strength has been established in elite climbers, their effect on recreational climbing is unknown. Therefore, the purpose of this study was to characterize the physiological and anthropometric characteristics of indoor climbers engaging in climbing at a recreational or noncompetitive setting. We hypothesized that heart rates and climbing durations would meet the standards set by the American College of Sports Medicine (ACSM) and Center for Disease Control and Prevention (CDC) for eliciting health benefits and that grip strength would decrease over the course of a typical climbing session. One hundred twenty-one male and female adult recreational climbers participated in this study. Following informed consent, subjects were instrumented with a heart rate monitor (Polar V800) which recorded heart rate and duration. Preclimb and postclimb grip strength were evaluated using a hand grip dynamometer and used to calculate fatigue. Subjects were 30.9 ± 8.3 years old and had participated in climbing for 5.6 ± 6.5 years. The average heart rate during climbing sessions was 122.3 ± 14.5 b·min-1, and session duration was 90.6 ± 31.3 minutes. Mean grip strength was 49.9 ± 11.2 kg, whereas the strength to mass ratio was 0.71 ± 0.14, and fatigue was 13.1 ± 11.6%. Results from the current study suggest that recreational indoor climbing elicits exercise heart rates and durations that are consistent with the CDC and ACSM's recommendations for cardiovascular health. Grip strength data suggested that forearm muscle fatigue may limit climbing durations.

Strength, Cardiovascular Fitness, and Blood Lipid Measures in Law Enforcement Personnel After a 12-Week Health Promotion Program.

ABSTRACT: Hibbert, JE, Klawiter, DP, Schubert, MM, Nessler, JA, and Asakawa, DS. Strength, cardiovascular fitness, and blood lipid measures in law enforcement personnel after a 12-week health promotion program. J Strength Cond Res 36(11): 3105-3112, 2022-Law enforcement personnel often have high rates of cardiovascular disease and injury. Health promotion programs have been found to successfully encourage behavior change among law enforcement personnel, but these programs can often be intensive and expensive. Thus, the purpose of this study was to examine the efficacy of a health promotion program on body composition, metabolic health, muscle strength, and cardiovascular endurance in law enforcement personnel. Active duty officers from a local law enforcement agency were invited to participate in a 12-week health promotion program that included activity tracking and exercise and nutrition education. Eighteen subjects underwent measurements of body composition, V̇ o2 max through treadmill test, knee extensor strength, and blood lipids. An a priori alpha level for significance was set at 0.05, and comparisons were assessed using paired t -tests. Overall, subjects improved blood lipid levels evidenced by movement of mean values toward established healthy ranges. Although 8 subjects improved their V̇ o2 max (range: 1.3-30% change), there was large variability and no statistically significant differences in measures of V̇ o2 max (pre: 38.48 ± 5.86 ml·kg·min -1 ; post: 39.27 ± 5.26 ml·kg·min -1 ), body composition (pre: 26.52 ± 8.02% body fat; post: 26.44 ± 7.45% body fat), and strength normalized to body mass (isometric pre: 1.45 ± 0.45; post: 1.08 ± 0.36). Although no significant changes were noted, promising trends in these data suggest that health promotion programs with a modified focus may lead to positive changes in overall health.

Forces at the Feet, Gait Timing, and Trunk Flexion/Extension Excursion While Walking with a Gear Belt or Gear Vest Load.

Law enforcement personnel often carry gear loads, which have a history of causing low back pain. The aim of this study was to evaluate the differences in gait and trunk posture for gear load carried on a gear belt and a gear vest. Twenty-nine participants performed load carriage in three conditions: a no load control trial (C), a symmetrically loaded gear belt (GB), and an anterior-loaded gear vest (ALV). Gear conditions had 9.07 kg of additional mass. Motion capture and insole force sensors were used to collect data while participants walked on a treadmill for three minutes per condition. Mean insole reaction force was significantly greater in both GB and ALV conditions as compared to C (p < 0.001). Mean gait cadence in the GB or ALV condition were not significantly different from the C condition. However, double support time in the ALV condition was significantly longer compared to C condition (p = 0.023). Stance duration on the left foot was significantly longer with the GB (p = 0.001) and ALV (p = 0.028) when compared to C. Results showed trunk flexion/extension excursion was significantly less in the GB condition when compared to the C condition (p = 0.002). These findings demonstrate that law enforcement and other personnel who walk while carrying gear loads may experience altered biomechanics compared to unloaded walking. Altered biomechanics and increased forces on the feet could potentially increase risk of musculoskeletal injury while carrying gear loads.

Upper limb manual dexterity, strength and blood flow after walking with backpack load.

This study aimed to characterize the effects of walking with backpack load on upper limb function. Fifteen males participated in 3 conditions: no load, 40% body weight loaded backpack (BP) and loaded backpack with simulated rifle (BRC). Pinch strength, grip strength, sensory threshold, blood flow volume, and a manual dexterity test were assessed before and after a 45-min walking trial. Pinch strength in the BP condition was significantly different than the control (p < 0.05). Grooved pegboard times were faster after a seated recovery (p = 0.026) than immediately after walking with load. Blood flow was significantly decreased to <53% of baseline (p ≤ 0.001) in BP and BRC immediately after donning the backpack. No significant changes in grip strength or sensory threshold were measured among conditions or time points. In conclusion, pinch strength, manual dexterity and blood flow were affected by backpack carriage, but other upper limb measures remained unaffected.

Fluid Loss in Recreational Surfers.

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 < 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 < 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.

Are the Kinetics and Kinematics of the Surf Pop-Up Related to the Anthropometric Characteristics of the Surfer?

The surf pop-up is a unique and challenging skill, critical to successful surfing. Hypothesizing that anthropometric characteristics of surfers influence the pop-up performance, we aimed to measure kinematics and ground-reaction forces (GRF) during a simulated pop-up motion, and to relate these variables with anthropometric characteristics. Twenty-three male surfers (age: 28.4 ± 10.1 years old; body mass: 68.3 ± 10.8 kg; height: 1.73 ± 0.07 m; time of practice: 12.4 ± 8.9 years; arm-span: 1.75 ± 8.9 m) perform a simulated pop-up in the laboratory, while GRF and 3D motion-capture data were acquired. The duration of the pop-up was 1.20 ± 0.19 s (60% push-up and 40% reaching/landing phase). During the push-up, the hands were placed 0.46 ± 0.05 m apart and generated a relative total peak-force of 0.99 ± 0.10 N/Weight, with symmetrical impulse of 0.30 ± 0.05 N·s/Weight for the dominant and 0.29 ± 0.07 N·s/Weight for the nondominant hand. Elbow angles were not different during the peak force application (110 ± 18° vs. 112 ± 18°, respectively) of the push-up phase. During the landing phase, the feet were placed 0.63 ± 0.10 m apart and generated a relative peak force of 1.63 ± 0.18 N/Weight. The impact force during landing was applied unevenly between the rear foot (28%) and the front foot (72%). In conclusion, most anthropometric-related variables showed no relationship with performance variables, with the exception of an inverse relationship between muscle mass and pop-up total duration. We also observed no differences in upper- and lower-body kinematics between the dominant vs. nondominant hands and among surfers who preferred a regular vs. "goofy-foot" stance. Finally, the force profiles between hands were similar and symmetric, while the lower extremities during the reaching phase were different, with the front foot applying greater force than that of the rear foot.

Energetics of Swimming With Hand Paddles of Different Surface Areas.

ABSTRACT: Crocker, GH, Moon, JF, Nessler, JA, and Newcomer, SC. Energetics of swimming with hand paddles of different surface areas. J Strength Cond Res 35(1): 205-211, 2021-Hand paddles are one of the most common training aids used by the competitive swimmer, yet little is known regarding how hand paddle surface area affects the metabolic cost of transport (COT) while swimming. The purpose of this study was to determine how altering hand paddle size affects energy use during submaximal, front-crawl (i.e., freestyle) swimming. Twenty-six proficient, adult swimmers (13 men and 13 women) completed six 3-minute trials in a flume at a constant pace (102 cm·s-1; 1:38 per 100 m). Trials were performed in random order, using 1 of 5 pairs of hand paddles of different sizes or no paddles at all. Paddle surface areas were 201, 256, 310, 358, and 391 cm2 per hand. Without paddles, COT, arm cadence, and distance per stroke were 7.87 ± 1.32 J·kg-1·m-1, 29.4 ± 4.9 min-1, and 2.13 ± 0.34 m, which corresponded to a rate of oxygen consumption (V̇o2) of 23.3 ± 3.7 ml·kg-1·min-1 and a heart rate (HR) of 118 ± 17 b·min-1. The use of larger hand paddles decreased COT, cadence, V̇o2, and HR and increased distance traveled per stroke (all p < 0.001). However, the magnitude of the change of COT decreased as paddle size increased, indicating diminishing marginal return with increasing paddle surface area. The largest sized paddles increased COT per stroke compared with swimming without paddles (p = 0.001). Therefore, results from this study suggest that an optimal hand paddle size exists (210-358 cm2) for proficient, adult swimmers, which reduces COT without increasing COT per stroke.

Characterization of Heart Rate Responses, Duration, and Distances Traveled in Youth Participating in Recreational Skateboarding at Community Skateparks.

ABSTRACT: Furr, HN, Nessler, JA, and Newcomer, SC. Characterization of heart rate responses, duration, and distances traveled in youth participating in recreational skateboarding at community skateparks. J Strength Cond Res 35(2): 542-548, 2021-Recreational skateboarding continues to gain popularity in youth within the United States and abroad. Surprisingly, there is a paucity of research regarding the cardiovascular responses of youth participating in recreational skateboarding. Therefore, the purpose of this study was to test the hypothesis that skateboarding would elicit heart rates and durations consistent with the American College of Sports Medicine (ACSM) and Center for Disease Control and Prevention (CDC) recommendations for cardiovascular fitness in youth. Seventy-one recreational skateboarders (boys: 63 and girls: 8) between the ages of 6 and 17 years participated in this study. Data were acquired at 9 skateparks in the local community. After parental consent, subjects completed a questionnaire and were instrumented with a heart rate monitor (Polar V800 GPS Sports Watch), which recorded heart rate, duration, and distance traveled. Subjects were instructed to engage in typical skateboarding activities, with the duration and intensity of activity determined by the individual. Subjects were 10.6 ± 2.9 years old and had participated in skateboarding for 3.1 ± 2.4 years. On average, subjects skateboarded 55.5 ± 28.4 minutes, at an average heart rate of 140.4 ± 16.1 b·min-1, and traveled an average distance of 2.65 ± 1.87 km. Results from this study suggest that youth participating in recreational skateboarding at community skateparks attain exercise intensities and durations that are comparable with the ACSM's and CDC's exercise recommendations for cardiovascular fitness in youth. These findings may hold implications for city planners considering the impact of community skateparks on physical activity in youth and overall public health.

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

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.

Sensorimotor synchronization during gait is altered by the addition of variability to an external cue.

Sensorimotor synchronization has been used in the rehabilitation of gait, yet much remains unknown regarding the optimal use of this technique. The purpose of this study was to test the hypothesis that adding small amounts of variability to the motion of a vertically oscillating treadmill would affect the behavior of healthy walkers. Sixteen young adults walked on a treadmill and pneumatically actuated platform for one control trial (no oscillation) and eight trials in which the walking surface oscillated in the vertical direction under different conditions of variability. During the oscillation trials, the mean frequency of oscillation was equal to the preferred step frequency of the participant, but each individual cycle period was allowed to vary within a pre-determined range from 0% (no variability) to ±25% (high variability) of the mean cycle period. The amount of variance of each cycle period within each condition was drawn randomly from a white noise generator. Synchronization was improved when a small amount of noise was added to the platform motion but synchronization significantly decreased at higher levels of noise. Coefficient of variation of stride duration was relatively unchanged at lower levels of variability, but increased significantly at higher levels of variability. Statistical persistence of stride duration was significantly reduced during all trials with vertical oscillation relative to normal walking, but was not significantly altered by variability in the treadmill oscillation. These results suggest that the addition of a small amount of random variability to the cycle period of an oscillator may enhance sensorimotor synchronization of gait to an external signal. These data may have implications for the use of synchronization in a therapeutic setting.

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

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.

A biomechanical analysis of the stand-up paddle board stroke: a comparative study.

BACKGROUND: Stand-up paddle boarding (SUP) is a rapidly growing global aquatic sport, with increasing popularity among participants within recreation, competition and rehabilitation. To date, few scientific studies have focused on SUP. Further, there is no research examining the biomechanics of the SUP paddle stroke. The purpose of this study was to investigate whether variations in kinematics existed among experienced and inexperienced SUP participants using three-dimensional motion analysis. This data could be of significance to participants, researchers, coaches and health practitioners to improve performance and inform injury minimization strategies. METHODS: A cross-sectional observational design study was performed with seven experienced and 19 inexperienced paddlers whereby whole-body kinematic data were acquired using a six-camera Vicon motion capture system. Participants paddled on a SUP ergometer while three-dimensional range of motion (ROM) and peak joint angles were calculated for the shoulders, elbows, hips and trunk. Mann-Whitney U tests were conducted on the non-normally distributed data to evaluate differences between level of expertise. RESULTS: Significant differences in joint kinematics were found between experienced and inexperienced participants, with inexperienced participants using greater overall shoulder ROM (78.9° ± 24.9° vs 56.6° ± 17.3°, p = 0.010) and less hip ROM than the experienced participants (50.0° ± 18.5° vs 66.4° ± 11.8°, p = 0.035). Experienced participants demonstrated increased shoulder motion at the end of the paddle stoke compared to the inexperienced participants (74.9° ± 16.3° vs 35.2° ± 28.5°, p = 0.001 minimum shoulder flexion) and more extension at the elbow (6.0° ± 9.2° minimum elbow flexion vs 24.8° ± 13.5°, p = 0.000) than the inexperienced participants. DISCUSSION: The results of this study indicate several significant kinematic differences between the experienced and inexperienced SUP participants. These variations in technique were noted in the shoulder, elbow and hip and are evident in other aquatic paddling sports where injury rates are higher in these joints. These finding may be valuable for coaches, therapists and participants needing to maximize performance and minimize injury risk during participation in SUP.

Skin Temperatures in Females Wearing a 2 mm Wetsuit during Surfing.

The aim of this investigation was to examine regional skin temperatures in recreational female surfers' wearing a 2 mm thick neoprene wetsuit while surfing and to compare these results to previously published data collected in males participating in an identical study. Female surfers (n = 27) engaged in surfing for at least 40 min while wearing a commercially available 2 mm full wetsuit. Skin temperature of eight different anatomical locations were measured with wireless iButton thermal sensors. Regional skin temperatures significantly differed (p < 0.001) across almost all anatomical regions. Furthermore, regional skin temperatures significantly decreased across time at all skin regions throughout an average surfing session (p < 0.001). The greatest reduction in skin temperature was observed in the lower leg (-5.4 °C). Females in the current study exhibited a significantly greater skin temperature decrease in the lower back (-15.2% vs. -10.8%, p = 0.022) and lower arm (-13.6% vs. -10.8%, p < 0.001) when compared to previous data published in males. Overall, results of the current study are consistent with data previously published on male recreational surfers. However, the current study provides preliminary evidence that the magnitude of change in skin temperature may differ between male and female recreational surfers at some anatomical locations.

Electromyographic Analysis of the Surf Paddling Stroke Across Multiple Intensities.

Nessler, JA, Ponce-Gonzalez, JG, Robles-Rodriguez, C, Furr, H, Warner, M, and Newcomer, SC. Electromyographic analysis of the surf paddling stroke across multiple intensities. J Strength Cond Res 33(4): 1102-1110, 2019-Surfers spend a majority of their time in the water paddling. The purpose of this study was to examine activity in 5 muscles that contribute to paddling at different velocities and to characterize oxygen use, paddling cadence, and surfboard motion at each velocity. Twelve recreational surfers completed an incremental paddling test on a short surfboard in a swim flume. Surface electromyography was recorded bilaterally from latissimus dorsi, upper and mid trapezius, and posterior and mid deltoid. Electromyographic activity increased as water velocity increased for all muscles, but the change in activation between endurance and sprint paddling was greatest for latissimus dorsi (p < 0.001). At higher water velocities, the middle deltoid was activated earlier in the paddling stroke (p = 0.005). Oxygen use, paddling cadence, and surfboard roll/yaw increased with increasing water velocity. These data may be useful for athletes, trainers, and equipment designers interested in increasing power and efficiency of the paddling stroke.

Differences in V[Combining Dot Above]O2peak of Surfers When Paddling in Water vs. on a Swimbench Ergometer.

Furr, HN, Warner, ME, Copeland, TL, Robles-Rodríguez, C, Ponce-González, JG, Nessler, JA, and Newcomer, SC. Differences in V[Combining Dot Above]O2peak of surfers when paddling in water vs. on a swimbench ergometer. J Strength Cond Res 33(4): 1095-1101, 2019-The purpose of this study was to test the hypothesis that surfers would achieve a higher V[Combining Dot Above]O2peak when tested in a swim flume vs. on a swimbench ergometer. Forty-eight surfers (male: 38, female: 10) aged 18-45 years participated in the study. Protocol 1 and 2 both measured heart rate, oxygen consumption (V[Combining Dot Above]O2), and respiratory exchange ratio while subjects performed an incremental paddling test both on a swimbench ergometer and in a swim flume. Protocol 2 additionally measured muscle activity and changes in skin temperature. V[Combining Dot Above]O2peak was significantly higher in the swim flume (33.03 ± 1.04 ml·kg·min) vs. on the swimbench ergometer (29.86 ± 1.08 ml·kg·min) (p value < 0.001). There were also significant differences in muscle activation and changes in skin temperature between the flume and ergometer (p-value < 0.05). Surfers significantly increased their V[Combining Dot Above]O2peak in the water suggesting previous reports of V[Combining Dot Above]O2peak likely underestimated surfer's aerobic fitness when measured on a swimbench ergometer. Future research investigating the aerobic fitness of surfers should be conducted while paddling in water or account for the 11% difference in V[Combining Dot Above]O2peak when tested on a swimbench ergometer.

Characterisation of regional skin temperatures in recreational surfers wearing a 2-mm wetsuit.

The purpose of this study was to investigate skin temperatures across surfers' bodies while wearing a wetsuit during recreational surfing. Forty-six male recreational surfers participated in this study. Participants were instrumented with eight wireless iButton thermal sensors for the measurement of skin temperature, a Polar RCX5 heart rate monitor and a 2-mm full wetsuit. Following instrumentation, participants were instructed to engage in recreational surfing activities as normal. Significant differences (p < 0.001) in skin temperature (Tsk) were found across the body while wearing a wetsuit during recreational surfing. In addition, regional skin temperature changed across the session for several regions of the body (p < 0.001), and the magnitude of these changes varied significantly between regions. We show for the first time that significant differences exist in skin temperature across the body while wearing a wetsuit during a typical recreational surfing session. These findings may have implications for future wetsuit design. Practitioner Summary: This study investigated the impact of wearing a wetsuit during recreational surfing on regional skin temperatures. Results from this study suggest that skin temperatures differ significantly across the body while wearing a 2-mm wetsuit during recreational surfing. These findings may have implications for future wetsuit design.

Wearing an Inflatable Vest Alters Muscle Activation and Trunk Angle While Paddling a Surfboard.

Low back pain is a commonly reported problem among recreational surfers. Some individuals report that wearing a vest with an inflatable bladder that alters trunk angle may help to alleviate pain. The purpose of this study was to determine whether such a vest has an effect on muscle activation and extension of the lower back. Twelve recreational surfers completed 12 paddling trials at 1.1 m/s in a swim flume on both a shortboard and a longboard on 2 separate days. Three conditions of no vest, vest uninflated, and vest inflated were presented to participants in random order. Surface EMG and trunk angle were acquired via wireless sensors placed over the right erector spinae, mid-trapezius, upper trapezius, and latissimus dorsi. Wearing the inflated vest affected muscle activation: erector spinae and mid-trapezius demonstrated a significant decrease in activation relative to wearing no vest (12% and 18% respectively, p < .05). Trunk extension was also significantly reduced when the vest was inflated (18% reduction, p < .05). Results were similar for both the short and longboard, though this effect was greater while paddling the larger board. These results suggest that a properly inflated vest can alter trunk extension and muscle activity while paddling a surfboard in water.