Countermovement Jump Recovery in Professional Soccer Players Using an Inertial Sensor

Purpose The purpose of this study was to assess the utility of an inertial sensor for assessing recovery in professional soccer players. Methods In a randomized, crossover design, 11 professional soccer players wore shorts fitted with phase change material (PCM) cooling packs or uncooled packs (control) for 3 h after a 90 minute match. Countermovement jump (CMJ) performance was assessed simultaneously with an inertial sensor and an optoelectric system, pre match, and 12, 36 and 60 h post match. Inertial sensor metrics were flight height, jump height, low force, countermovement distance, force at low point, rate of eccentric force development, peak propulsive force, maximum power, and peak landing force. The only optoelectric metric was flight height. CMJ decrements, and effect of PCM cooling were assessed with repeated measures ANOVA. Jump heights were also compared between devices. Results For the inertial sensor data there were decrements in CMJ height on the days after matches (88±10% of baseline at 36 h P=0.012, effect size 1.2, for control condition) and accelerated recovery with PCM cooling (105±15% of baseline at 36 h, P=0.018 vs. control, effect size 1.1). Flight heights were strongly correlated between devices (r=0.905, P<0.001) but inertial sensor values were 1.8±1.8 cm lower (P=0.008). Low force during countermovement was increased (P=0.031) and landing force was decreased (P=0.043) after matches, but neither were affected by the PCM cooling intervention. Other CMJ metrics were unchanged after matches. Conclusions This small portable inertial sensor provides a practical means of assessing recovery in soccer players

The Effect of Carbohydrate Beverage Ingestion on Central versus Peripheral Fatigue: A Placebo-Controlled, Randomized Trial in Cyclists

Purpose: We investigated whether carbohydrate ingestion delays fatigue in endurance-trained cyclists via peripheral or central mechanisms. Methods: Ten men [35±9 yrs] and ten women [42±7 yrs] were assigned, in a double-blind, cross-over design to a sports drink [CHO] and placebo [PL]. Strength measures were made 3 times [pre-exercise, post-time trial and post-ride to exhaustion]: 1) Maximal voluntary contraction [MVC]; 2) MVC with superimposed femoral nerve magnetic stimulation to measure central activation ratio [CAR]; 3) femoral nerve stimulation in a 3-second pulse train on relaxed muscle. Subjects cycled 2 hours at ~65% of peak oxygen consumption [VO2peak], with 5 1-minute sprints interspersed, followed by a 3-km time trial. After strength testing, cyclists remounted their bikes, performed a brief warmup, and pedaled at ~85% VO2peak until unable to maintain workload. Changes in metabolic and strength measurements were analyzed with repeated measures ANOVA. Results: From pre-exercise to post-time trial: MVC declined in men (17%) and women (18%) [p=0.004] with no effect of beverage [p>0.193]; CAR decreased in both sexes with PL [P=0.009], the decline was attenuated by CHO in men only [time×treatment, p=0.022]; there was no evidence of peripheral fatigue in either sex with either beverage [p>0.122]. Men rode faster in the time trial with CHO [p=0.005] but did not improve performance in the ride to exhaustion [p=0.080]. In women, CHO did not improve performance in the time trial [p=0.173], or in the ride to exhaustion [p=0.930]. Conclusion: Carbohydrate ingestion preserved central activation and performance in men, but not women, during long-duration cycling.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Motion of the multi-segmented spine in elite dancers during passé and arabesque

Background The spinal biomechanics of dance tasks have received little study and no studies have used a multi-segmented spinal model. Knowledge of how the segments of the spine move may be useful to the dance clinician and dance educator. Research question What is the direction and amount of motion of the primary segments of the spine in elite dancers during an arabesque and a passé? Methods This observational study examined 59 elite dancers performing an arabesque and a passé using a three-dimensional motion analysis system with the trunk divided into a series of five segments: pelvis, lower lumbar, upper lumbar, lower thoracic and upper thoracic spine. Results For the arabesque, all spinal segments moved in the same direction within each plane and the majority of total spinal motion occurred in the thoracic spine. Thoracic segments were at or near end range position at completion of the arabesque. For the passé, the spinal segments moved in different directions within each plane and the majority of total spinal motion occurred in the lumbar spine. Significance Dance clinicians and dance educators may benefit from the knowledge that thoracic hypomobility in any plane may limit arabesque performance and that attempts to instruct dancers to achieve a position of passé without flexion of the lumbar spine may be a valid aesthetic ideal but also an unrealistic functional expectation

Multi-segment spine range of motion in dancers with and without recent low back pain

Background Altered spine kinematics are a common in people with LBP. This may be especially true for populations such as dancers, who are required to perform repetitive movements of the spine, although this remains unclear. Research question Do dancers with recent LBP display altered spine kinematics compared to their asymptomatic counterparts? Methods A cross-sectional study of multi-segment spine kinematics was performed. Forty-seven pre-professional and professional female dancers either with LBP in the past two months (n = 26) or no LBP in the past 12 months (n = 21) participated. Range of motion (ROM) during standing side bending, seated rotation, and walking gait were compared. Results Female dancers with LBP displayed reduced upper lumbar transverse plane ROM in seated rotation (Effect Size (ES)= −0.61, 95% Confidence Interval (CI): −1.20, 0.02, p = 0.04), as well as reduced lower lumbar transverse plane ROM (ES=−0.65, 95% CI: −1.24, −0.06, p = 0.03) in gait. However, there was increased lower thoracic transverse plane ROM (ES = 0.62, 95% CI: 0.04, 1.21, p = 0.04) during gait. No differences in the frontal plane were observed. Significance Altered transverse plane spine kinematics were evident in dancers with recent LBP for select segments and tasks. This may reflect a protective movement strategy. However, as the effect sizes of observed differences were moderate, and the total number of differences between groups was small, collectively, it seems only subtle differences in spine kinematics differentiate dancers with LBP to dancers without