Human Biomechanical and Cardiopulmonary Responses to Partial Gravity – A Systematic Review

The European Space Agency has recently announced to progress from low Earth orbit missions on the International Space Station to other mission scenarios such as exploration of the Moon or Mars. Therefore, the Moon is considered to be the next likely target for European human space explorations. Compared to microgravity (µg), only very little is known about the physiological effects of exposure to partial gravity (µg < partial gravity < 1 g). However, previous research studies and experiences made during the Apollo missions comprise a valuable source of information that should be taken into account when planning human space explorations to reduced gravity environments. This systematic review summarizes the different effects of partial gravity (0.1-0.4 g) on the human musculoskeletal, cardiovascular and respiratory systems using data collected during the Apollo missions as well as outcomes from terrestrial models of reduced gravity with either 1 g or microgravity as a control. The evidence-based findings seek to facilitate decision making concerning the best medical and exercise support to maintain astronauts’ health during future missions in partial gravity. The initial search generated 1323 publication hits. Out of these 1323 publications, 43 studies were included into the present analysis and relevant data were extracted. None of the 43 included studies investigated long-term effects. Studies investigating the immediate effects of partial gravity exposure reveal that cardiopulmonary parameters such as heart rate, oxygen consumption, metabolic rate and cost of transport are reduced compared to 1 g, whereas stroke volume seems to increase with decreasing gravity levels. Biomechanical studies reveal that ground reaction forces, mechanical work, stance phase duration, stride frequency, duty factor and preferred walk-to-run transition speed are reduced compared to 1 g. Partial gravity exposure below 0.4 g seems to be insufficient to maintain musculoskeletal and cardiopulmonary properties in the long-term. To compensate for the anticipated lack of mechanical and metabolic stimuli some form of exercise countermeasure appears to be necessary in order to maintain reasonable astronauts’ health, and thus ensure both sufficient work performance and mission safety

COMFORT AND PLANTAR PRESSURE PATTERN DURING RUNNING WITH PREFABRICATED INSOLES

The aim of this study was to investigate the relationship between plantar pressure pattern and wearing comfort of five different prefabricated insoles. Therefore wearing comfort was assessed by a questionnaire and the use of a visual analogue scale (VAS) and plantar pressure was measured by a Pedar-­X system. For statistical analysis single factor ANOVA for repeated measurements, Bonferroni and Pearson correlation test were performed. Significant differences in comfort ratings and average maximum plantar pressure were found. A relationship between average plantar pressure and comfort could not be detected. Nevertheless prefabricated insoles are able to improve wearing comfort of running shoes. Additional parameters like insole hardness and/or flexibility might also influence wearing comfort and seems to modulate the plantar pressure pattern during running

JOINT SPECIFIC MECHANICAL POWER DURING VERTICAL JUMPS OF ELITE BOBSLEIGH ATHLETES

The purpose of the study was to quantify jumping mechanics of elite male bobsleigh athletes (N=10; 28?3 yrs; 193?5 cm; 99?8 kg) performing two different kinds of vertical jumps (squat and countermovement). Kinetics and kinematics were measured with two force platforms (one per leg, 1080 Hz) and eight high-speed infrared cameras sampled at 120 Hz. Detection of the joint specific mechanical power generation pattern between legs and across athletes was realized via inverse-dynamic calculation. The results show an average jumping height of about 50 cm, which is associated with average body mass of almost 100 kg. An average joint specific contribution of mechanical power generation during squad and countermovement jumps could be determined close to one third per joint (hip, knee, ankle)

FOOTWEAR AFFECTS GEARING IN THE MUSCULO-SKELETTAL SYSTEM IN RUNNING

The purpose of this study was to evaluate the impact of barefoot running on grass versus shod running regarding the effectivness of running mechanics. Fourteen male runners performed five valid running trials at 4.0m/s ± 0.2. Running kinetics and running kinematics were recorded for one barefoot and five shod conditions. The comparison of barefoot and shod running showed different effects concerning the gear ratio at the ankle and knee joint. Running with shoes showed mechanical advantages at the ankle joint in the first, second and fifth part of the ground reaction phase but caused disadvantages at the knee joint

ISCHEMIC PRECONDITIONING BLUNTS ECCENTRIC EXERCISE-INDUCED MUSCLE DAMAGE DUE TO REDUCED OXIDATIVE STRESS?

The purpose of this study was to investigate if ischemic preconditioning (IPC) prior to eccentric exercise of the elbow flexors leads to alterations in muscle oxygen saturation (SmO2) during loading. Additionally, parameters of muscle damage, like serum creatine kinase, were assessed following the loading protocol. Nineteen untrained males were allocated into two groups: (1) performing IPC prior to eccentric exercise (IPC+ECC; n=10) and (2) performing eccentric exercise only (n=9). Muscle damage parameters were significantly lower in IPC+ECC (p2 during eccentric loading (ischemia) as well as the subsequent increase of SmO2 (reperfusion) were lower in IPC+ECC (

METHOD EVALUATION TO DETERMINE HYDRATION STATES OF TENDONS BY USING MRI

Due to the fact that water content is a determinant of the material properties of tendons and therefore might affect sports performance and the risk of injury, the purpose of this pilot study was to evaluate the reliabilityand sensitivity of a MRI based method to quantify content of a tendon. For this pilot study twenty porcine digital flexor tendons were chosen. All samples were examined on a MR scanner using three 3D ultra-short echo time sequences. With the applied sequences it was possible to determine a decrease in water content of the tendons. In addition, the methods showed a good inter session reliability. Further investigations are needed to improve the upper and lower limit of resolution regarding the physiological hydration state

DIFFERENCES BETWEEN TAKE-OFF BEHAVIOR DURING VERTICAL JUMPS AND TWO ARTISTIC ELEMENTS

The present study analysed the possible application of vertical jumps as a diagnostic tool for the acrobatic elements backward somersault (6s) and Menichelli (MEN). Therefore, 14 female gymnasts of the German national squad performed dassical vertical jumps (CMJ, SJ, DJ), backward somersaults and Menichellis during a diagnostic camp at the German Research Centre of Elite Sport (momentum). Kinematic and kinetic parameters were captured by a 30-motion capture system and two force plates. Take off velocities of the CMJ and backward somersault showed significant correlations (r=0.86). Besides possible predictions for take4ff velocity of BS performing CMJ, findings did not address execution of MEN. Concerning training purposes, vertical jumping does not affect performance characteristics of acrobatic elements

Synergistic research synthesis enabling evidence based practice

Introduction Evidence based practice requires showing upon what we are basing medical opinions and guidelines, or recognising when evidence is absent that guidance is “expert opinion” and research is required to fill evidence gaps. Aerospace is one of the final medical fields to begin organising a critical summary, adapted periodically, of evidence underpinning operations, and the Aerospace Medicine Systematic Review Group is a new initiative to fill this gap. This group facilitates high quality, transparent synthesis of evidence, to inform operational medical guidelines in best practice, while simultaneously guiding future research by identifying research gaps. The group has (A) facilitated a second review with the European Space Agency Medical Office to inform human Lunar and Martian mission medical considerations and (B) developed and published, open access, new review methods to aid others to undertake aerospace medicine systematic reviews. Methods (A) Electronic databases were searched from the start of records to April 2016. Studies were assessed with the Cochrane risk of bias tool. Effect size analysis was used to assess the effect of various g loading on human biomechanical and cardiopulmonary systems. (B) A new rating scale to appraise technical principles of studies to simulate partial gravity was implemented. Additional method guides for developing questions, protocol drafting, data extracting, quantifying effects and scoring a bed rest study quality were also developed. Results (A) The review identified 43 studies that found partial gravity appears unable to protect against cardiovascular and biomechanical changes. (B) The group designed and developed a website (www.aerospacemed.rehab/systematic-review-group) to provide free access to methods developed by the group and provide links to wider resources. Discussion The systematic review informed medical considerations for future human exploration missions and demonstrates how systematic synthesis of the evidence base more strongly and better informs medical operations than expert opinion, basic reviews or disordered individual studies. Limitations in the current conduct and reporting of aerospace medicine research are also highlighted. Continuing development of review methods, published as open access guides on the group website and working with review teams globally, will help bring synergy to, and enable high quality summary, of the aerospace medicine evidence base

JOINT SPECIFIC CONTRIBUTION OF MECHANICAL POWER AND WORK DURING ACCELERATION AND TOP SPEED IN ELITE SPRINTERS

The purpose of the study was to quantify and compare sprint mechanics of elite female sprinters (N=9; PB 11.4?0.2s) during acceleration (1st, 2nd, 3rd step) and top speed (‘flying 30m) running. Three dimensional kinetics and kinematics were measured on an IAAF indoor track armed with four force plates and 16 cameras. The comparison between the 1st, 2nd and 3rd step and the ‘flying 30m’ (vave= 9.0?0.2 ms-1) shows a progressive change in absorption and generation of mechanical power. Whilst the knee extensors where able to minimize energy absorption during acceleration, the ankle extensors showed a stretch-shortening cycle and a small absorption from the first step. This energy loss at the ankle joint does not necessarily leads to a decrease in sprint performance, it also offers the plantar flexors to work in an stretch-shortening cycle instead of concentric only mode