Transitioning between different sensory environments is known to affect sensorimotor function and postural control. Water immersion presents a novel environmental stimulus common to many professional and recreational pursuits, but is not well-studied with regard to its sensorimotor effects upon transitioning back to land. The authors investigated the effects of long-duration water immersion on terrestrial postural control outcomes in veteran divers. Eleven healthy men completed a 6-hour thermoneutral pool dive (4.57 m) breathing diver air. Center of pressure was observed before and 15 minutes after the dive under 4 conditions: (1) eyes open/stable surface (Open-Stable); (2) eyes open/foam surface (Open-Foam); (3) eyes closed/stable surface (Closed-Stable); and (4) eyes closed/foam surface (Closed-Foam). Postdive decreases in postural sway were observed in all testing conditions except for Open-Stable. The specific pattern of center of pressure changes in the postdive window is consistent with (1) a stiffening/overregulation of the ankle strategy during Open-Foam, Closed-Stable, and Closed-Foam or (2) acute upweighting of vestibular input along with downweighting of somatosensory, proprioceptive, and visual inputs. Thus, our findings suggest that postimmersion decreases in postural sway may have been driven by changes in weighting of sensory inputs and associated changes in balance strategy following adaptation to the aquatic environment.
Stephen M. Glass, Christopher K. Rhea, Matthew W. Wittstein, Scott E. Ross, John P. Florian and F.J. Haran
Fabian Mager, Jim Richards, Malika Hennies, Eugen Dötzel, Ambreen Chohan, Alex Mbuli and Felix Capanni
Forefoot stiffness has been shown to influence joint biomechanics. However, little or no data exist on metatarsophalangeal stiffness. Twenty-four healthy rearfoot strike runners were recruited from a staff and student population at the University of Central Lancashire. Five repetitions of shod, self-selected speed level walking, and jogging were performed. Kinetic and kinematic data were collected using retroreflective markers placed on the lower limb and foot to create a 3-segment foot model using the calibrated anatomical system technique. Ankle and metatarsophalangeal moments and angles were calculated. Stiffness values were calculated using a linear best fit line of moment versus of angle plots. Paired t tests were used to compare values between walking and jogging conditions. Significant differences were seen in ankle range of motion, but not in metatarsophalangeal range of motion. Maximum moments were significantly greater in the ankle during jogging, but these were not significantly different at the metatarsophalangeal joint. Average ankle joint stiffness exhibited significantly lower stiffness when walking compared with jogging. However, the metatarsophalangeal joint exhibited significantly greater stiffness when walking compared with jogging. A greater understanding of forefoot stiffness may inform the development of footwear, prosthetic feet, and orthotic devices, such as ankle foot orthoses for walking and sporting activities.
Mary Emily Littrell, Young-Hui Chang and Brian P. Selgrade
Clinically, measuring gait kinematics and ground reaction force (GRF) is useful to determine the effectiveness of treatment. However, it is inconvenient and expensive to maintain a laboratory-grade gait analysis system in most clinics. The purpose of this study was to validate a Wii Balance Board, Kinovea motion-tracking software, and a video camera as a portable, low-cost system, and overground gait analysis system. We validated this low-cost system against a multicamera Vicon system and research-grade force platform (Advanced Mechanical Technology, Inc). After validation trials with known weights and angles, 5 subjects walked across an instrumented walkway for multiple times (n = 8/subject). We collected vertical GRF and segment angles. Average GRF data from the 2 systems were similar, with peak GRF errors below 3.5%BW. However, variability in the balance board’s sampling rate led to large GRF errors early and late in stance, when the GRF changed rapidly. The thigh, shank, and foot angle measurements were similar between the single and multicamera, but the pelvis angle was far less accurate. The proposed system has the potential to provide accurate segment angles and peak GRF at low cost but does not match the accuracy of the multicamera system and force platform, in part because of the Wii Balance Board’s variable sampling rate.
Chadwick Debison-Larabie, Bernadette A. Murphy and Michael W.R. Holmes
This study examined sex differences in head kinematics and neck muscle activity during sudden head perturbations. Sixteen competitive ice hockey players participated. Three muscles were monitored bilaterally using surface electromyography: sternocleidomastoid, scalene, and splenius capitis. Head and thorax kinematics were measured. Head perturbations were induced by the release of a 1.5-kg weight attached to a wire wrapped around an adjustable pulley secured to the participant’s head. Perturbations were delivered in 4 directions (flexion, extension, right lateral bend, and left lateral bend). Muscle onset times, muscle activity, and head kinematics were examined during 3 time periods (2 preperturbation and 1 postperturbation). Females had significantly greater head acceleration during left lateral bend (31.4%, P < .05) and flexion (37.9%, P = .01). Females had faster muscle onset times during flexion (females = 51 ± 11 ms; males = 61 ± 10 ms; P = .001) and slower onset times during left lateral bend and extension. Females had greater left/right sternocleidomastoid and scalene activity during extension (P = .01), with no difference in head acceleration. No consistent neuromuscular strategy could explain all directional sex differences. Females had greater muscle activity postperturbation during extension, suggesting a neuromuscular response to counter sudden acceleration, possibly explaining the lack of head acceleration differences.
Laura K. Fewell, Riley Nickols, Amanda Schlitzer Tierney and Cheri A. Levinson
The current study tested if athlete patients differed from non-athlete patients in measures of eating disorder (ED) and related pathology. Athlete (n = 91 in Study 1; n = 39 in Study 2) and non-athlete (n = 76 in Study 1; n = 26 in Study 2) patients completed self-report measures, and body mass index (BMI) was calculated. Athlete patients had significantly lower ED symptomatology and depression than non-athlete patients (ps < .05). ED impairment, worry, psychosocial functioning, BMI, obsessive-compulsiveness, and compulsive exercise did not significantly differ between groups (ps > .08). Greater ED symptomatology was associated with higher psychosocial functioning among athlete patients and higher obsessive-compulsive symptoms and compulsive exercise among non-athlete patients. This is a novel study comparing ED symptomatology and related measures of mental health in athlete and non-athlete patients engaged in residential or partial hospitalization ED treatment. Future research should further investigate how participation in high-level sport impacts the presentation, treatment, and outcome of individuals with EDs.
Uta Kraus, Sophie Clara Holtmann and Tanja Legenbauer
Disordered eating in athletes has been frequently studied with a particular emphasis on aesthetic sports. Lately, competitive rowing has come into the focus. It has been supposed that in competitive rowers eating disturbances occur more frequently compared to non-competitive rowers. The aim of the present study therefore is to investigate eating disturbances and mental health related issues in competitive and non-competitive rowers. N = 45 lightweight (LWR), n = 31 heavyweight (HWR) and n = 37 non-competitive rowers (NCR) participated in an online based survey during the beginning of the on-season asking for eating behaviour (SCOFF, EDI-2) and mental health problems (PHQ). Results showed that competitive rowers reported more eating disturbances and risky attitudes/behaviour compared to non-competitive rowers. LWR showed higher Drive for thinness compared to HWR. The regression analysis revealed that Drive for thinness and Bulimia predict eating disorder symptoms in rowers. These results emphasize the presence of serious eating disturbances in competitive rowing.
Jenny H. Conviser, Amanda Schlitzer Tierney and Riley Nickols
Eating disorders (EDs) and disordered-eating behaviors (DEBs), pose a high risk of morbidity and mortality, threatening physical health, emotional health, and overall quality of life. Unfortunately, among athletes, prevalence rates continue to increase. This document summarizes the challenges of establishing and navigating the multidisciplinary care needed to effectively treat EDs and DEBs among athletes. The benefits of timely and frequent communication within the multidisciplinary treatment team (MDTT) are emphasized and discussed. Authors advise who should be selected as members of the MDTT and suggest that all personnel, including athletic coaches, athletic trainers, physical therapists, and certified fitness professionals be ED-informed and ED-sensitive. Vital components of care are noted including use of a variety of evidence-based psychotherapeutic modalities, interventions which target emotional regulation, and prioritize values based compassionate care. Authors caution that performance decrements and medical/physiological changes are not always easily observable in individuals with EDs and DEBs and therefore, attuned, consistent, and ongoing monitoring is needed. Consensus regarding previously established parameters for return to play and careful titration of physical activity throughout the ED recovery process are suggested as important for preserving health, preventing re-injury, or relapse and facilitating successful return to sport participation.
Katie A. Conway, Randall G. Bissette and Jason R. Franz
Aging and many gait pathologies are characterized by reduced propulsive forces and ankle moment and power generation during trailing leg push-off in walking. Despite those changes, we posit that many individuals retain an underutilized reserve for enhancing push-off intensity during walking that may be missed using conventional dynamometry. By using a maximum ramped impeding force protocol and maximum speed walking, we gained mechanistic insight into the factors that govern push-off intensity and the available capacity thereof during walking in young subjects. We discovered in part that young subjects walking at their preferred speed retain a reserve capacity for exerting larger propulsive forces of 49%, peak ankle power of 43%, and peak ankle moment of 22% during push-off—the latter overlooked by maximum isometric dynamometry. We also provide evidence that these reserve capacities are governed at least in part by the neuromechanical behavior of the plantarflexor muscles, at least with regard to ankle moment generation. We envision that a similar paradigm used to quantify propulsive reserves in older adults or people with gait pathology would empower the more discriminate and personalized prescription of gait interventions seeking to improve push-off intensity and thus walking performance.
Andrea S. Hartmann, Florian Steenbergen, Silja Vocks, Dirk Büsch and Manuel Waldorf
Fitness training to attain the lean body ideal is becoming increasingly popular among women. However, it remains unclear how the drive for leanness (DL), as compared to the drives for thinness (DT) and muscularity (DM), relates to body image pathology and substance use in female weight-trainers. Participants (N = 168) completed a survey assessing DL, DT, DM, eating and body dysmorphic disorder pathology, and substance use. DT and DM were related to eating disorder and body dysmorphic disorder symptoms (all r ≥ .29; all ps < .01), while DL only to the former (r = .19, p < .05). Supplement use was associated with DL and DM (r = .17 and .55; both p < .01) and pharmaceutical use with DT and DM (r ≥ .21; both p < .01). Female weight-trainers should not be neglected in body image disorder prevention, with a particular focus on DT and DM.
Hiroaki Hobara, Sakiko Saito, Satoru Hashizume, Hiroyuki Sakata and Yoshiyuki Kobayashi
To understand the step characteristics during sprinting in lower-extremity amputees using running-specific prosthesis, each athlete should be investigated individually. Theoretically, sprint performance in a 100-m sprint is determined by both step frequency and step length. The aim of the present study was to investigate how step frequency and step length correlate with sprinting performance in elite unilateral transtibial amputees. By using publicly-available Internet broadcasts, the authors analyzed 88 races from 7 unilateral transtibial amputees. For each sprinter’s run, the average step frequency and step length were calculated using the number of steps and official race time. Based on Pearson’s correlation coefficients between step frequency, step length, and official race time for each individual, the authors classified each individual into 3 groups: step-frequency reliant, step-length reliant, and hybrid. It was found that 2, 2, and 3 sprinters were classified into step-frequency reliant, step-length reliant, and hybrid, respectively. These results suggest that the step frequency or step length reliance during a 100-m sprint is an individual occurrence in elite unilateral transtibial amputees using running-specific prosthesis.