Performance-determining physiological factors in the luge start

Integrating patient-reported and performance-based measurements for addressing nonspecific low back pain in young office workers

BACKGROUND

Non-specific low back pain (LBP) is a major health concern associated with a sedentary lifestyle. Understanding the multifactorial risk factors is essential for developing effective management and prevention strategies.

PURPOSE

This study aims to evaluate how posture, muscle activity and strength imbalances, pain levels, and emotional awareness collectively contribute to the subjective functional status of young office workers with chronic nonspecific LBP, in order to assess the need for a holistic, biopsychosocial approach to managing this condition.

METHODS

A cross-sectional study, involving 102 office workers, including 64 females and 38 males, both healthy and suffering from chronic nonspecific LBP, was conducted. The average age of subjects was 31 years (standard deviation = 6.6). The study combined objective assessments, such as posture evaluation, muscle electrical activity, and strength imbalances with patient-reported outcomes (PRO) to investigate their correlations with subjective functional status.

RESULTS

Significant correlations and subsequent inclusion in the multivariate linear regression model identified vertebral rotation, muscle activity and strength disparities as key predictors. PRO, including pain levels and emotional awareness also significantly influenced the Spine Functional Index. Collectively, these factors explained 46.8% of the variance in the subjective functional status among subjects.

CONCLUSION

This study underscores the importance of a holistic approach in understanding nonspecific LBP, integrating objective measures with PRO to reveal the intricate relationship between functional status and diverse influencing factors. Our findings advocate for the adoption of the biopsychosocial model, demonstrating how the interplay of health conditions, body structures, and social factors impacts chronic nonspecific LBP.

Does Moderate-Load Priming Activity Influence Maximal Upper-Body Performance and Perceptual State?

ABSTRACT

Harrison, PW, Kelly, VG, Jenkins, DG, McGuigan, MR, Holmberg, PM, and James, LP. Does moderate-load priming activity influence maximal upper-body performance and perceptual state?. J Strength Cond Res 37(11): e581-e587, 2023-The results of previous research indicate that resistance exercise "priming" may improve strength-power measures within 48 hours after their completion. Although researchers have primarily examined performance responses after lower-body priming stimuli, investigations examining the effects of upper-body resistance priming exercises are presently limited. Therefore, the aim of this study was to examine upper-body pushing and pulling performance in addition to perceptual responses 3 and 27 hours after moderate-load (ML) upper-body resistance priming exercise. Fourteen resistance-trained men were assigned to complete ML priming (4 × 3 bench press and bench pull at 65% 1RM [repetition maximum]) and control (rest) protocols in a randomized and counterbalanced order. Peak velocity during the bench throw and bench pull tests involving different loads (25, 50, and 75% 1RM) showed no practical change at 3 and 27 hours after the priming session (p = 0.216-0.99, Cliff's d = -0.041 to 0.225). Small effect size increases in perceptual measures ("physical feeling," "physical performance," "aggression" [p = 0.400-0.553, Cliff's d = 0.183-0.201], and "muscular heaviness" [p = 0.178, Cliff's d = 0.231]) were found at 3 hours postpriming. A moderate practical increase was observed in perceived "physical feeling" compared with control (p = 0.385, Cliff's d = 0.349) in addition to small effect size increases in perceived "physical performance" and "aggression" (Cliff's d = 0.243-0.290) at 27 hours after priming activities. These results indicate that upper-body strength-power changes within 27 hours after ML upper-body resistance exercise priming are not practically meaningful.

Sport-specific training induced adaptations in postural control and their relationship with athletic performance

Effects of various exercise programs on postural balance control in athletes and their underlying physiological mechanisms have been extensively investigated. However, little is known regarding how challenging sport-specific conditions contribute to the improvement of body balance and to what extent these changes may be explained by sensorimotor and/or neuromuscular function adaptations. Analysis of the literature could provide useful information on the interpretation of changes in postural sway variables in response to long-term sport-specific training and their association with performance measures. Therefore, the aim of this scoping review was (1) to analyze the literature investigating postural control adaptations induced by sport-specific training and their relationship with measures of athletic performance, and (2) to identify gaps in the existing research and to propose suggestions for future studies. A literature search conducted with Scopus, Web of Science, MEDLINE and Cochrane Library was completed by Elsevier, SpringerLink and Google Scholar with no date restrictions. Overall, 126 articles were eligible for inclusion. However, the association between variables of postural balance control and measures of sport-specific performance was investigated in only 14 of the articles. A relationship between static and/or dynamic balance and criterion measures of athletic performance was revealed in shooting, archery, golf, baseball, ice-hockey, tennis, and snowboarding. This may be ascribed to improved ability of athletes to perform postural adjustments in highly balanced task demands. However, the extent to which sport-specific exercises contribute to their superior postural stability is unknown. Although there is a good deal of evidence supporting neurophysiological adaptations in postural balance control induced by body conditioning exercises, little effort has been made to explain balance adaptations induced by sport-specific exercises and their effects on athletic performance. While an enhancement in athletic performance is often attributed to an improvement of neuromuscular functions induced by sport-specific balance exercises, it can be equally well ascribed to their improvement by general body conditioning exercises. Therefore, the relevant experiments have yet to be conducted to investigate the relative contributions of each of these exercises to improving athletic performance.

The Role of Neuromuscular Control of Postural and Core Stability in Functional Movement and Athlete Performance

Balance and core stabilization exercises have often been associated with improved athlete performance and/or decreased incidence of injuries. While these exercises seem to be efficient in the prevention of injuries, there is insufficient evidence regarding their role in sport-specific performance and related functional movements. The aim of this scoping review is (1) to map the literature that investigates whether currently available variables of postural and core stability are functionally related to athlete performance in sports with high demands on body balance and spinal posture and (2) to identify gaps in the literature and suggest further research on this topic. The literature search conducted on MEDLINE, Scopus, Web of Science, PubMed, and Cochrane Library databases was completed by Google Scholar, SpringerLink, and Elsevier. Altogether 21 articles met the inclusion criteria. Findings revealed that postural stability plays an important role in performance in archery, biathlon, gymnastics, shooting, and team sports (e.g., basketball, hockey, soccer, tennis). Also core stability and strength represent an integral part of athlete performance in sports based on lifting tasks and trunk rotations. Variables of these abilities are associated with performance-related skills in cricket, cycling, running, and team sports (e.g., baseball, football, hockey, netball, soccer, tennis). Better neuromuscular control of postural and core stability contribute to more efficient functional movements specific to particular sports. Training programs incorporating general and sport-specific exercises that involve the use of postural and core muscles showed an improvement of body balance, back muscle strength, and endurance. However, there is controversy about whether the improvement in these abilities is translated into athletic performance. There is still a lack of research investigating the relationship of body balance and stability of the core with sport-specific performance. In particular, corresponding variables should be better specified in relation to functional movements in sports with high demands on postural and core stability. Identifying the relationship of passive, active, and neural mechanisms underlying balance control and spinal posture with athlete performance would provide a basis for a multifaced approach in designing training and testing tools addressing postural and core stability in athletes under sport-specific conditions.

Olympic Sports Science-Bibliometric Analysis of All Summer and Winter Olympic Sports Research

Introduction: The body of scientific literature on sports and exercise continues to expand. The summer and winter Olympic games will be held over a 7-month period in 2021-2022. Objectives: We took this rare opportunity to quantify and analyze the main bibliometric parameters (i.e., the number of articles and citations) across all Olympic sports to weigh and compare their importance and to assess the structure of the "sport sciences" field. The present review aims to perform a bibliometric analysis of Olympic sports research. We quantified the following topics: (1) the most investigated sports; (2) the main journals in which the studies are published; (3) the main factors explaining sport-specific scientific attractiveness; (4) the influence of being in the Olympic programme, economic weight, and local influences on research output; and (5) which research topic is the most investigated across sports. Methods: We searched 116 sport/exercise journals on PubMed for the 40 summer and 10 winter Olympic sports. A total of 34,038 articles were filtered for a final selection of 25,003 articles (23,334 articles on summer sports and 1,669 on winter sports) and a total of 599,820 citations. Results and Discussion: Nine sports [football (soccer), cycling, athletics, swimming, distance & marathon running, basketball, baseball, tennis, and rowing] were involved in 69% of the articles and 75% of the citations. Football was the most cited sport, with 19.7 and 26.3% of the total number of articles and citations, respectively. All sports yielded some scientific output, but 11 sports (biathlon, mountain biking, archery, diving, trampoline, skateboarding, skeleton, modern pentathlon, luge, bobsleigh, and curling) accumulated a total of fewer than 50 publications. While ice hockey is the most prominently represented winter sport in the scientific literature, winter sports overall have produced minor scientific output. Further analyses show a large scientific literature on team sports, particularly American professional sports (i.e., baseball, basketball, and ice hockey) and the importance of inclusion in the Olympic programme to increasing scientific interest in "recent" sports (i.e., triathlon and rugby sevens). We also found local/cultural influence on the occurrence of a sport in a particular "sport sciences" journal. Finally, the relative distribution of six main research topics (i.e., physiology, performance, training and testing, injuries and medicine, biomechanics, and psychology) was large across sports and reflected the specific performance factors of each sport.

Physical Abilities in Low Back Pain Patients: A Cross-Sectional Study with Exploratory Comparison of Patient Subgroups

An abundance of literature has investigated the association between low back pain (LBP) and physical ability or function. It has been shown that LBP patients display reduced range of motion, decreased balance ability, impaired proprioception, and lower strength compared to asymptomatic persons. The aim of this study was to investigate the differences between LBP patients and healthy controls in terms of several physical abilities. Based on the premised that different biomechanical and physiological causes and consequences could be related to different types of LBP, a secondary exploratory attempt of the study was to examine the differences between LBP subgroups based on the pain location (local or referred) or type of pathology (discogenic or degenerative) on the level of impairment of function and ability. Participants performed range of motion tests, trunk maximal voluntary contraction force tests, a sitting balance assessment, the timed up-and-go test, the chair rise test, and the trunk reposition error test. Compared to the control group, symptomatic patients on average showed 45.7% lower trunk extension (p < 0.001, η² = 0.33) and 27.7 % lower trunk flexion force (p < 0.001, η² = 0.37) during maximal voluntary contraction. LBP patients exhibited decreased sitting balance ability and lower scores in mobility tests (all p < 0.001). There were no differences between groups in Schober’s test and trunk repositioning error (p > 0.05). No differences were observed among the LBP subgroups. The exploratory analyses are limited by the sample size and uncertain validity of the diagnostic procedures within this study. Further studies with appropriate diagnostic procedures and perhaps a different subgrouping of the LBP patients are needed to elucidate if different types of LBP are related to altered biomechanics, physiology, and function.

The effects of heavy upper-body strength training on ice sledge hockey sprint abilities in world class players

The current study investigated the effects of 6 weeks of heavy upper-body strength training on maximal strength and sprint abilities in eight world class ice sledge hockey players. Before and after the strength training intervention, all subjects performed a 30-m maximal sprint on ice (where time for each 10 m section was measured) and 1 repetition maximal (1RM) strength test in the bench pull (BP), pull-down (PD), pull over (PO) and front pull (FP) exercises. Three weekly sessions with 3×6-8RM for these strength exercises were added during the intervention period. From pre- to post-test, 1RM in the strength exercises improved by 4-8%, whereas 30-m sprint time, all 10-m section times and the calculated power output in the 10-m acceleration phase all improved by 2-3% (all P<.05). The pre- to post-test changes in 30-m sprint time and the initial 10-m time correlated significantly with the changes in 1RM for BP (r=0.59 and 0.55) and PD (r=0.60 and 0.68) (all P<.05). In conclusion, the results of this study strongly suggest that heavy upper-body strength training improves upper-body strength and ice sledge hockey sprint abilities, and that the magnitude of improvements in strength correlates with the improvements in sprint abilities.

On the relationship between upper-body strength, power, and sprint performance in ice sledge hockey

Ice sledge hockey is a popular paralympic team sport where players rely entirely on their upper body to propel themselves rapidly across the ice surface. The isolated and repetitive poling movements provide a good model for examining upper-body sprint ability and the related movement and strength characteristics. Therefore, the purpose of the present study was to investigate the relationship between upper-body maximal strength, power, and sprint performance in ice sledge hockey. Thirteen male ice sledge hockey players from the Norwegian national team performed three 30-m maximal sprint tests recorded by fixed light sensors. The best 30-m time for each subject was used for further analyses, and the sprint was analyzed more in detail for the first and last 10-m split times and kinematics (cycle length and rate) using photocells and 2-dimensional video analysis. One repetition maximum (1RM) strength and peak power were assessed in the bench press, bench pull, and pull-down exercises using a barbell and a linear encoder. Both 1RM strength and peak power for all the 3 strength exercises correlated significantly with the total sprint time (-0.75 < r < - 0.86, all p < 0.005), the first (0.60 < r < 0.72, all p < 0.05), and the last (0.74 < r < 0.83, all p < 0.05) 10-m split times in the 30-m sprint test. There were no significant relationships between sprint kinematics and 1RM strength and peak power. Overall, these results demonstrate that there are close relationships between upper-body strength, power, and sprint performance in highly trained athletes and that the ability to produce propulsion and high frequency in combination is important for the sprint abilities in ice sledge hockey.

Development of a measurement and feedback training tool for the arm strokes of high-performance luge athletes

Previous studies have shown that the start plays a critical role in sliding events and explains more than 55% of the variance of the final time in luge. Experts evaluate the contribution of the arm strokes to be 23% of the total starting performance. The aim of the present study was to develop a measurement and feedback training tool (Speedpaddler) for the arm strokes of high-performance luge athletes. The construction is an aluminium alloy framework with a customary belt conveyor system, which is driven by two synchronized servo motors. Training is possible with constant speeds up to 12 m · s(-1) or several speed curves, which simulate the acceleration of different luge tracks. The construction facilitates variations in the inclination and speed of the conveyor belts and thereby the resistance and movement speed. If the athlete accelerates the conveyor belts during arm-paddling, the torque of the motors decreases. Torque measurements and high-speed video offer valuable insights into the several technique criteria. Comparisons of arm-paddle cycle durations on ice and on the Speedpaddler with 18 luge athletes (national team and juniors) showed no statistical differences. The Speedpaddler might be a useful tool to improve starting performance all year round.

Balance ability and athletic performance

The relationship between balance ability and sport injury risk has been established in many cases, but the relationship between balance ability and athletic performance is less clear. This review compares the balance ability of athletes from different sports, determines if there is a difference in balance ability of athletes at different levels of competition within the same sport, determines the relationship of balance ability with performance measures and examines the influence of balance training on sport performance or motor skills. Based on the available data from cross-sectional studies, gymnasts tended to have the best balance ability, followed by soccer players, swimmers, active control subjects and then basketball players. Surprisingly, no studies were found that compared the balance ability of rifle shooters with other athletes. There were some sports, such as rifle shooting, soccer and golf, where elite athletes were found to have superior balance ability compared with their less proficient counterparts, but this was not found to be the case for alpine skiing, surfing and judo. Balance ability was shown to be significantly related to rifle shooting accuracy, archery shooting accuracy, ice hockey maximum skating speed and simulated luge start speed, but not for baseball pitching accuracy or snowboarding ranking points. Prospective studies have shown that the addition of a balance training component to the activities of recreationally active subjects or physical education students has resulted in improvements in vertical jump, agility, shuttle run and downhill slalom skiing. A proposed mechanism for the enhancement in motor skills from balance training is an increase in the rate of force development. There are limited data on the influence of balance training on motor skills of elite athletes. When the effectiveness of balance training was compared with resistance training, it was found that resistance training produced superior performance results for jump height and sprint time. Balance ability was related to competition level for some sports, with the more proficient athletes displaying greater balance ability. There were significant relationships between balance ability and a number of performance measures. Evidence from prospective studies supports the notion that balance training can be a worthwhile adjunct to the usual training of non-elite athletes to enhance certain motor skills, but not in place of other conditioning such as resistance training. More research is required to determine the influence of balance training on the motor skills of elite athletes.

An approximate simulation model for initial luge track design

Competitive and recreational sport on artificial ice tracks has grown in popularity. For track design one needs knowledge of the expected speed and acceleration of the luge on the ice track. The purpose of this study was to develop an approximate simulation model for luge in order to support the initial design of new ice tracks. Forces considered were weight, drag, friction, and surface reaction force. The trajectory of the luge on the ice track was estimated using a quasi-static force balance and a 1d equation of motion was solved along that trajectory. The drag area and the coefficient of friction for two runs were determined by parameter identification using split times of five sections of the Whistler Olympic ice track. The values obtained agreed with experimental data from ice friction and wind tunnel measurements. To validate the ability of the model to predict speed and accelerations normal to the track surface, a luge was equipped with an accelerometer to record the normal acceleration during the entire run. Simulated and measured normal accelerations agreed well. In a parameter study the vertical drop and the individual turn radii turned out to be the main variables that determine speed and acceleration. Thus the safety of a new ice track is mainly ensured in the planning phase, in which the use of a simulation model similar to this is essential.