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Carrying a load in one hand (30 kg) resulted in more spine load than splitting the same load between both hands (15 kg). When carrying double the load in both hands (30 kg in each hand vs. 30 kg in one hand), spine load decreased, suggesting merit in balancing load when designing work.

In swimming, the underwater phase after the start and turn comprises gliding and dolphin kicking, with the latter also known as underwater undulatory swimming (UUS). Swimming performance is highly dependent on the underwater phase; therefore, understanding the training effects in UUS and underwater gliding can be critical for swimmers and coaches.Further, the development of technique in young swimmers can lead to exponential benefits in an athlete's career. This study aimed to evaluate the effects of a training protocol on UUS and underwater gliding performance and kinematics in young swimmers. Seventeen age group swimmers (boys =10, girls =7) performed maximal UUS and underwater gliding efforts before and after a seven-week training protocol. Time to reach 10 m; intra-cyclic mean, peak, and minimum velocities; and gliding performance improved significantly after the training protocol. The UUS performance improvement was mostly produced by an improvement of the upbeat execution, together with a likely reduction of swimmers' hydrodynamic drag.Despite the changes in UUS and gliding, performance was also likely influenced by growth.The findings from this study highlight kinematic variables that can be used to understand and quantify changes in UUS and gliding performance.

Labile surfaces in the form of suspension straps are increasingly being used as a tool in resistance training programs. Pushing is a common functional activity of daily living and inherently part of a well-rounded training program. This study examined pushing exercises performed on stable surfaces and unstable suspension straps, specifically muscle activation levels and spine loads were quantified together with the influence of employing technique coaching. There were several main questions that this study sought to answer: Which exercises challenged particular muscles? What was the magnitude of the resulting spine load? How did stable and unstable surfaces differ? Did coaching influence the results? Fourteen men were recruited as part of a convenience sample (mean age, 21.1 ± 2.0 years; height, 1.77 ± 0.06 m; mean weight, 74.6 ± 7.8 kg). Data were processed and input to a sophisticated and anatomically detailed 3D model that used muscle activity and body segment kinematics to estimate muscle force-in this way, the model was sensitive to the individuals choice of motor control for each task; muscle forces and linked segment joint loads were used to calculate spine loads. Exercises were performed using stable surfaces for hand/feet contact and repeated where possible with labile suspension straps. Speed of movement was standardized across participants with the use of a metronome for each exercise. There were gradations of muscle activity and spine load characteristics to every task. In general, the instability associated with the labile exercises required greater torso muscle activity than when performed on stable surfaces. Throughout the duration of an exercise, there was a range of compression; the TRX push-up ranged from 1,653 to 2,128.14 N, whereas the standard push-up had a range from 1,233.75 to 1,530.06 N. There was no significant effect of exercise on spine compression (F(4,60) = 0.86, p = 0.495). Interestingly, a standard push-up showed significantly greater shear than TRX angle 1 (p = 0.02), angle 2 (p = 0.01), and angle 3 (p = 0.02). As with any training program for the elite or recreational athlete alike, specific exercises and programs should reflect one's injury history, capabilities, limitations, and training goals. Although none of the exercises examined here breached the NIOSH action limit for compression, those exercises that produced higher loads should be used relative to the individual. Thus, the atlas of muscle activation, compression, and shear forces provided can be used to create an appropriate program. Those individuals not able to tolerate certain loads may refer to the atlas and choose exercises that minimize load and still provide sufficient muscle activation. Conversely, an individual with a resilient back that requires an increased muscular challenge may choose exercises with higher muscle activation and spine load. This helps the individual, trainer, or coach in program design respecting individual differences and training goals.

BACKGROUND/OBJECTIVE: Given the possible links between movement, fitness and injury, the goal of this study was to evaluate strength, endurance, and hip range of motion (ROM) (i.e. fitness); movement quality; and age in a population of firefighters. PARTICIPANTS: Male firefighters (n = 282), all members of a major Canadian city fire department, volunteered to participate in this cross-sectional study. METHODS: Torso endurance, grip strength, pull-ups, hip ROM, movement quality (sum of 7 movement tasks graded on a 0-3 scale), age, body mass, height, body mass index, and hip and waist circumference were assessed in 282 Firefighters. Relationships between variables were evaluated and compared to relevant populations (i.e. police officers, other firefighters, athletes, students and healthy males). RESULTS: There was no relationship between age and fitness or movement quality. Compared to other populations, our firefighter population had poorer torso endurance but similar grip strength. Larger body mass, waist circumference and hip width were correlated (p < 0.01) with poorer Total Movement Score. Back extensor endurance (Biering-Sorensen test) was found to have the strongest relationship with Total Movement Score in comparison to all other tests. Notably, the extensor endurance and pull-ups were related to five of nine tasks each. The magnitude of hip ROM asymmetry related only to the stand-sit-stand movement test. In general, correlations between variables were relatively low, suggesting that most of these variables are independent and/or unrelated to one another. CONCLUSIONS: Movement quality is not strongly correlated with traditionally utilized markers of fitness, nor is movement linked to age. This would imply that training should include movement competency components together with traditional fitness objectives.

Worker-centered injury prevention can be described as fitting workers to tasks by improving fitness and modifying movement patterns; however, the current results show weak correlations between strength, endurance and ROM, and the way individuals move. Therefore, the development of occupation-specific injury prevention strategies may require both fitness and movement-oriented objectives.

Background Higher neck strength has been postulated to reduce head impact magnitude during purposeful heading in football. Objectives This pilot trial explored the effect of a neck exercise programme on (1) neck strength and (2) head impact magnitude during heading in male and female adolescent football players. Methods Boys and girls (aged 12–17 years) were randomised by team to the intervention (5 weeks of supervised neuromuscular neck exercises integrated into part 2 of the FIFA 11 + , completed three times per week) or the control group (usual part 2 of the FIFA 11 + , no neck exercises). Outcomes included isometric neck strength and head impact magnitude (peak linear acceleration and peak angular velocity) during standardised heading from a throw-in (at baseline and 6 weeks) plus completion of an evaluation survey by intervention players and coaches. Results In total, 52 players ( n = 31 intervention; n = 21 control) completed the study. Mixed-model analysis of variance (ANOVA) revealed significant differences in neck strength variables ( p < 0.001), peak linear acceleration ( p = 0.04) and peak angular velocity ( p = 0.04) between the intervention and control groups over time. Intervention players demonstrated increases in mean composite neck strength (53.8% intervention vs 15.6% control) as well as decreases in mean peak linear head acceleration during heading (− 11.8% vs − 5.0%) from baseline to follow-up. Reduction in peak angular velocity was more pronounced in girls (− 27.7%) than boys (− 11.5%) in the intervention group. The addition of neck exercises into part 2 of the FIFA 11 + was feasible and accepted by players and coaches. Conclusion On average, players who completed neck exercises demonstrated an increase in isometric neck strength and a decrease in head impact magnitude during heading. These exercises were easily incorporated into usual training. Australian New Zealand Clinical Trials Registry (no: ACTRN12619001375145). Supplementary Information The online version contains supplementary material available at 10.1007/s40279-021-01564-0.

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