IntroductionThe aims of this study were to examine reliability of treadmill running kinematics: i) during two different intensity, energy expenditure matched, runs ii) at two time points within each run iii) using two different methods of statistical analysis.MethodsTwenty healthy club distance runners performed two high intensity interval runs (HIIT) and two medium intensity continuous runs (MICR). Kinematics during ground contact were analysed in all three planes of motion at the ankle, knee, and hip. Maximum angle and range of motion were identified and for Functional Data Analysis (FDA) all of the collected data was utilised. Reliability was established from both discrete points and FDA using intraclass correlation coefficient (ICC), standard error of measurement (SEM) and minimum detectable change (MDC). In addition, coefficient of variation (CV) was calculated for discrete points, however, this was not possible for FDA.ResultsBoth discrete point analysis and FDA showed acceptable reliability in all three planes of motion. Only three variables produced SEM values higher than 5.0 degrees while ICC values ranged from poor to excellent.DiscussionThere were no differences in reliability between the start and end of the runs for HIIT or MICR. Gait kinematics during treadmill running were reliable across intensities, run type and time frames.

The present study examined the cardiovascular, metabolic, neuromuscular and perceptual effects of low-intensity jumping in simulated lunar gravity (∼20% bodyweight) with blood flow restriction (BFR). Fourteen healthy adults (24 ± 4 years; 1.81 ± 0.06 m; 75 ± 12 kg) completed an incremental jumping test in simulated lunar gravity (9.5° head-up tilt suspension) followed by a graded exercise test to determine maximal oxygen uptake ( V . O 2 peak ). Two exercise visits (with and without BFR) were completed on separate days comprising 6 × 2 min of low-intensity (40% V . O 2 peak ) continuous jumping at ∼20% bodyweight, with 1-min passive rest periods. Blood flow restriction was applied at 60% limb occlusion pressure to the lower limbs during the exercise periods and removed during the rest periods. Jumping in simulated lunar gravity with BFR, compared to without BFR, significantly decreased muscle tissue oxygenation within the vastus lateralis (∼20%) and gastrocnemius medialis (∼5%), and increased heart rate (10-23 beats min-1), carbon dioxide output (2-4 mL kg-1 min-1) and minute ventilation (7-16 L min-1). Oxygen consumption was either unaffected or slightly elevated up to 3 mL kg-1 min-1. Blood lactate concentration was significantly greater during BFR jumping by ∼1-2 mmol L-1. Pre-post exercise knee extension peak force declined in both conditions to similar extents. Perceived exertion, discomfort and body instability significantly increased with BFR. Jumping in simulated lunar gravity with BFR requires little equipment and elicits similar metabolic, cardiovascular and perceptual responses to BFR aerobic exercise in terrestrial settings (e.g., BFR walking/cycling), and therefore may have value as a musculoskeletal and cardiovascular exercise countermeasure during planetary exploration missions.

OBJECTIVES:Compare the efficacy and acceptability of low load blood flow restriction (BFR) using two different limb occlusion pressures (LOP) on pain and function in individuals with lower-limb musculoskeletal injury (MSKI) and associated persistent pain. DESIGN:Randomised controlled trial within a military residential rehabilitation setting. PARTICIPANTS:Twenty-eight individuals (N = 21 male; N = 7 female) with lower-limb MSKI were randomly allocated into: 1) BFR-RE with 80% LOP (BFR80), or 2) BFR-RE with 40% LOP (BFR40). Both groups completed 7x BFR-RE sessions during 5-days of residential rehabilitation at 20% 1-repetition maximum. MAIN OUTCOME MEASURES:The primary outcome measure was the Brief Pain Inventory (BPI). Secondary outcomes include injury-specific outcomes, pain pressure threshold (PPT) and lower-limb muscle strength assessment. All reported outcomes reflect changes in scores. RESULTS:BPI 'worst' displayed a time × group interaction (p = .013), driven by higher pain in BFR80 from pre-to post-intervention (standardised mean difference [SMD] = 1.532, p = .006). There was a significant time × group interaction for BPI 'severity' (p = .022), driven by significant between-group differences at T3 (BFR80-BFR40: SMD = 1.305, p = .015). PPTs improved within-session and over time. CONCLUSION:Both pressures demonstrated cumulative exercise-induced hypoalgesia via rising PPTs. BFR80 reported increased 'worst' pain score. Lower LOP may better preserve training volume and exercise tolerability.

Musculoskeletal injuries are commonly accompanied by acute and persistent pain; the latter of which can lead to maladaptive neurophysiological changes including central sensitisation and altered pain modulation responses. Blood flow restriction (BFR) exercise uses a pneumatic tourniquet to restrict arterial blood flow into the exercising limbs and has emerged as a promising rehabilitation tool, eliciting exercise-induced hypoalgesia (EIH) and increasing muscular strength and mass, but at lower external loads/intensities. The relationship between BFR tourniquet pressure and pain response is, however, complex. This review explores the mechanisms underpinning BFR-induced hypoalgesia and hyperalgesia across clinical and healthy populations. Findings indicate that while BFR exercise can reduce pain, potentially via metabolic, vascular, neurological, and psychological pathways, higher occlusive pressures or individual susceptibility, particularly in those with persistent pain, may provoke hyperalgesia. Mechanistically, this may involve inflammatory cytokine release, upregulated conditioned pain modulation and altered endorphin or endocannabinoid signalling. Psychological factors such as catastrophising and kinesiophobia may, furthermore, exacerbate nociceptive responses. These findings collectively highlight the pleiotropic and potentially hormetic nature of BFR exercise in pain modulation. Careful prescription, pressure selection, and patient monitoring are vital to maximise analgesic benefits while minimising adverse pain responses.

Background Musculoskeletal injury (MSKI) is the leading cause of medical downgrading and discharge within the UK military, with lower limb MSKI having the greatest incidence, negatively impacting operational readiness. Pain is a primary limiting factor to rehabilitation progress following MSKI. Heavy-load resistance training (RT; ie, loads >70% 1-repetition maximum) is traditionally used but may be contraindicated due to pain, potentially prolonging recovery and leading to failure of essential physical employment standards for UK military personnel. Low-load RT with blood flow restriction (BFR) can promote favourable morphological and physiological adaption, as well as elicit hypoalgesia in healthy and clinical populations (eg, post-operative), and has proven a viable option in military rehabilitation settings. The acceptability and tolerance of higher relative BFR pressures in persistent pain populations are unknown due to the complexity of presentation and the perception of discomfort experienced during BFR exercise. Greater relative pressures (ie, 80% limb occlusion pressure (LOP)) elicit a greater hypoalgesic response in pain-free individuals, but greater perceived discomfort which may not be tolerated in persistent pain populations. However, lower relative pressure (ie, 40% LOP) has elicited hypoalgesia in pain-free individuals, which therefore may be more clinically acceptable and tolerated in persistent pain populations. The primary aim of both randomised controlled trials (RCT) is to investigate the efficacy and acceptability of using high-frequency, low-load BFR-RT in UK military personnel with lower limb MSKI where persistent pain is the primary limiting factor for progression.Methodology The presented protocol is a two-phase RCT based within a military rehabilitation setting. Phase One is a 1-week RCT to determine the most efficacious and acceptable BFR-RT protocol (7× BFR-RT sessions over 5 days at 40% or 80% LOP; n=28). Phase Two is a 3-week RCT comparing the most clinically acceptable BFR pressure, determined by Phase One (21× BFR-RT sessions over 15 days; n=26) to usual care within UK Defence Rehabilitation residential rehabilitation practices. Outcomes will be recorded at baseline, daily and following completion of the intervention. The primary outcome will be the brief pain inventory. Secondary outcomes include blood biomarkers for inflammation and pain (Phase Two only), injury-specific outcome measures, lower extremity function scale, objective measures of muscle strength and neuromuscular performance, and pressure pain threshold testing.Ethics and dissemination The study is approved by the Ministry of Defence Research Ethics Committee (2318/MODREC/24) and Northumbria University. All study findings will be published in scientific peer-reviewed journals and presented at relevant scientific conferences.Trial registration number Registered with Clinical Trials. The registration numbers are as follows: NCT06621914 (Phase One) and NCT06621953 (Phase Two).

The Moon's gravitational field strength (17% Earth's gravity) may facilitate the use of bodyweight jumping as an exercise countermeasure against musculoskeletal and cardiovascular deconditioning in reduced gravity settings. The present study characterised the acute physiological and kinetic responses to bodyweight jumping in simulated Lunar gravity. Nineteen healthy adults (age: 25 ± 7 years, weight: 73 ± 11 kg; height: 1.81 ± 0.05 m, : 50 ± 11 mL kg −1 min −1 ) performed an incremental jumping test in simulated Lunar gravity (9.5° head‐up tilt suspension) comprising 4‐min stages of jumping with 1‐min rests, beginning at 30 cm and increasing 5 cm per stage up to 70 cm. A graded exercise test (GXT) to volitional exhaustion was subsequently performed using upright cycle ergometry. Cardiorespiratory outcomes (, , , breathing frequency, respiratory exchange ratio and heart rate (HR)) and peak vertical ground reaction forces (vGRF) increased linearly ( R 2 = 0.77–0.97) and blood lactate concentrations increased exponentially with jump height ( R 2 = 0.98). Participants achieved HRs of 158 ± 17 beats min −1 (88 ± 9% HR max ), metabolic rates of 35 ± 6 mL kg −1 min −1 (71 ± 9% ), blood lactate concentrations of 5.8 ± 1.7 mmol L −1 and peak vGRFs of 119 ± 17% bodyweight. Jumping at ∼20% bodyweight requires no equipment, allows for submaximal cardiovascular exercise intensities with and without blood lactate accumulation, and may have value as an exercise countermeasure in Lunar/Martian surface habitats.

Abstract Background Persistent pain is a complicated phenomenon associated with a wide array of complex pathologies and conditions (e.g., complex regional pain syndrome, non-freezing cold injury), leading to extensive disability and reduced physical function. Conventional resistance training is commonly contraindicated in load compromised and/or persistent pain populations, compromising rehabilitation progression and potentially leading to extensive pharmacological intervention, invasive procedures, and reduced occupational status. The management of persistent pain and utility of adjunct therapies has become a clinical and research priority within numerous healthcare settings, including defence medical services. Main Body Blood flow restriction (BFR) exercise has demonstrated beneficial morphological and physiological adaptions in load-compromised populations, as well as being able to elicit acute hypoalgesia. The aims of this narrative review are to: (1) explore the use of BFR exercise to elicit hypoalgesia; (2) briefly review the mechanisms of BFR-induced hypoalgesia; (3) discuss potential implications and applications of BFR during the rehabilitation of complex conditions where persistent pain is the primary limiting factor to progress, within defence rehabilitation healthcare settings. The review found BFR application is a feasible intervention across numerous load-compromised clinical populations (e.g., post-surgical, post-traumatic osteoarthritis), and there is mechanistic rationale for use in persistent pain pathologies. Utilisation may also be pleiotropic in nature by ameliorating pathological changes while also modulating pain response. Numerous application methods (e.g., with aerobic exercise, passive application, or resistance training) allow practitioners to cater for specific limitations (e.g., passive, or contralateral application with kinesiophobia) in clinical populations. Additionally, the low-mechanical load nature of BFR exercise may allow for high-frequency use within residential military rehabilitation, providing a platform for conventional resistance training thereafter. Conclusion Future research needs to examine the differences in pain modulation between persistent pain and pain-free populations with BFR application, supporting the investigation of mechanisms for BFR-induced hypoalgesia, the dose-response relationship between BFR-exercise and pain modulation, and the efficacy and effectiveness of BFR application in complex musculoskeletal and persistent pain populations.

Human movement has evolved within Earth's gravitational environment (1 g ; −9.81 m s −2 ). Future human exploration of terrestrial bodies, including the Moon (0.17 g ; −1.62 m s −2 ) and Mars (0.38 g ; −3.71 m s −2 ), will require astronauts to live and work within reduced gravitational environments (hypogravity). Progressing understanding of the physiological and biomechanical implications of movement in hypogravity will play a key role in supporting the expansion of humanity to terrestrial bodies beyond Earth, within our solar system. Ground‐based hypogravity analogues that enable the study of human movement are pivotal to developing knowledge in this field. Whole‐body suspension can serve as a resource‐efficient and accessible hypogravity analogue, yet only a limited number of such analogues exist globally. This technical report introduces a new hypogravity analogue facility: the Variable Gravity Suspension System (VGSS). The report introduces the VGSS and its theoretical framework, which enables simulation of both micro‐ and hypo‐gravity, presents proof‐of‐concept data regarding its ability to simulate hypogravity, and demonstrates the ability of the VGSS to facilitate locomotive and jumping activities in simulated hypogravity.

AbstractBlood flow restriction (BFR) has been identified as a potential countermeasure to mitigate physiological deconditioning during spaceflight. Guidelines recommend that tourniquet pressure be prescribed relative to limb occlusion pressure (LOP); however, it is unclear whether body tilting or reduced gravity analogues influence LOP. We examined LOP at the leg and arm during supine bedrest and bodyweight suspension (BWS) at 6° head‐down tilt (HDT), horizontal (0°), and 9.5° head‐up tilt (HUT) positions. Twenty‐seven adults (age, 26 ± 5 years; height, 1.75 ± 0.08 m; body mass, 73 ± 12 kg) completed all tilts during bedrest. A subgroup (n = 15) additionally completed the tilts during BWS. In each position, LOP was measured twice in the leg and arm using the Delfi Personalized Tourniquet System after 5 min of rest and again after a further 5 min. The LOP at the leg increased significantly from 6° HDT to 9.5° HUT in bedrest and BWS by 9–15 mmHg (Cohen's d = 0.7–1.0). Leg LOP was significantly higher during BWS at horizontal and 9.5° HUT postures relative to the same angles during bedrest by 8 mmHg (Cohen's d = 0.6). Arm LOP remained unchanged between body tilts and analogues. Intraclass correlation coefficients for LOP measurements taken after an initial and subsequent 5 min rest period in all conditions ranged between 0.91–0.95 (leg) and 0.83–0.96 (arm). It is advised that LOP be measured before the application of a vascular occlusion in the same body tilt/setting to which it is applied to minimize discrepancies between the actual and prescribed tourniquet pressure.

Space agencies plan crewed missions to the Moon and Mars. However, microgravity-induced lumbopelvic deconditioning, characterized by an increased fat fraction (FF) due to reduced physical activity, poses a significant challenge to spine health. This study investigates the spatial distribution of FF in the lumbopelvic muscles to identify the most affected regions by deconditioning, utilizing a computer-vision model and a tile-based approach to assess FF changes. Twenty-four healthy individuals (8 F) were recruited, and automatic segmentation of the lumbopelvic muscles was applied before and after 59 days of head-down tilt bed rest (HDTBR + 59) and 13 days of reconditioning (R + 13). Axial Dixon sequence images were acquired from 3 T magnetic resonance imaging. FF in the lumbar multifidus (LM), lumbar erector spinae (LES), quadratus lumborum, psoas major, gluteus maximus (GMax), gluteus medius (GMed), and gluteus minimus (GMin) muscles from the upper margin of L1 vertebra to the inferior border of GMax muscle were automatically derived using a computer-vision model. Lumbar muscles were segmented into eight tiles (superficial and deep, lateral to medial), and gluteal muscles into regions (anterior/superior for GMed and GMin, superior/inferior for GMax). At HDTBR + 59, the deep centrolateral region at L5/S1 for LM (18.7 ± 15.7%, P < 0.001; d = 0.97) and the deep medial region at Upper L4 for LES (5.4 ± 5.9%, P < 0.001; d = 0.34) showed the largest increase in FF compared with baseline data collection. These regions did not recover at R + 13 (P < 0.05; d ≥ 0.25). These findings highlight the need to target deep fascicles of LM and LES in countermeasure strategies to mitigate microgravity-induced lumbopelvic deconditioning, optimizing spine health, and performance.NEW & NOTEWORTHY This study reveals novel insights into fat fraction changes in lumbopelvic muscles after 60 days of head-down bed rest and 13 days of reconditioning. Lipids increased in the deep regions of the lumbar multifidus (LM) and lumbar erector spinae (LES), particularly at lower vertebral levels, and persisted after reconditioning. These findings highlight the need to target deep fascicles of LM and LES in future countermeasures to mitigate microgravity-induced deconditioning and optimize spine health.

Modern wearable monitors and laboratory equipment allow the recording of high-frequency data that can be used to quantify human movement. However, currently, data analysis approaches in these domains remain limited. This article proposes a new framework to analyze biomechanical patterns in sport training data recorded across multiple training sessions using multilevel functional models. We apply the methods to subsecond-level data of knee location trajectories collected in 19 recreational runners during a medium-intensity continuous run (MICR) and a high-intensity interval training (HIIT) session, with multiple steps recorded in each participant-session. We estimate functional intra-class correlation coefficient to evaluate the reliability of recorded measurements across multiple sessions of the same training type. Furthermore, we obtained a vectorial representation of the three hierarchical levels of the data and visualize them in a low-dimensional space. Finally, we quantified the differences between genders and between two training types using functional multilevel regression models that incorporate covariate information. We provide an overview of the relevant methods and make both data and the R code for all analyses freely available online on GitHub. Thus, this work can serve as a helpful reference for practitioners and guide for a broader audience of researchers interested in modeling repeated functional measures at different resolution levels in the context of biomechanics and sports science applications.

BACKGROUND CONTEXT: Prolonged bedrest induces accumulation of intramuscular lipid concentration (ILC) in the lumbar musculature; however, spatial distribution of ILC has not been determined. Artificial gravity (AG) mitigates some adaptations induced by 60 day bedrest by creating a head-to-feet force while participants are in a supine position. PURPOSE: To quantify the spatial distribution of accumulation of ILC in the lumbar musculature after 60 day bedrest, and whether this can be mitigated by AG exposure. STUDY DESIGN: Prospective longitudinal study. PATIENT SAMPLE: Twenty-four healthy individuals (8 females) participated in the study: Eight received 30 min continuous AG (cAG); Eight received 6 x 5 min AG (iAG), interspersed with rests; Eight were not exposed to AG (CRTL). OUTCOME MEASURES: From 3T magnetic resonance imaging (MRI), axial images were selected to assess lumbar multifidus (LM), lumbar erector spinae (LES), quadratus lumborum (QL), and psoas major (PM) muscles from L1/L2 to L5/S1 intervertebral disc levels. Chemical shift-based 2-echo lipid and/or water Dixon sequence was used to measure tissue composition. Each lumbar muscle was segmented into four equal quartiles (from medial to lateral). METHODS: Participants arrived at the facility for the baseline data collection before undergoing a 60 day strict 6 degrees head-down tilt (HDT) bedrest period. MRI of the lumbopelvic region was conducted at baseline and Day-59 of bedrest. Participants performed all activities, including hygiene, in 6 degrees HDT and were discouraged from moving excessively or unnecessarily. RESULTS: At the L4/L5 and L5/S1 intervertebral disc levels, 60-day bedrest induced a greater increase in ILC in medial and lateral regions (similar to+4%) of the LM than central regions (similar to+2%; p<.05). A smaller increase in ILC was induced in the lateral region of LES (similar to+1%) at L1/L2 and L2/L3 than at the centro-medial region (similar to+2%; p<.05). There was no difference between CRTL and intervention groups. CONCLUSIONS: Inhomogeneous spatial distribution of accumulation of ILC was found in the lumbar musculature after 60 day bedrest. These findings might reflect pathophysiological mechanisms related to muscle disuse and contribute to localized lumbar spine dysfunction. Altered spatial distribution of ILC may impair lumbar spine function after prolonged body unloading, which could increase injury risk to vulnerable soft tissues, such as the lumbar intervertebral discs. These novel results may represent a new biomarker of lumbar deconditioning for astronauts, bedridden, sedentary individuals, or those with chronic back pain. Changes are potentially modifiable but not by the AG protocols tested here. (C) 2021 The Authors. Published by Elsevier Inc.

Reduced muscle size and accumulation of paraspinal muscle fat content (PFC) have been reported in lumbopelvic muscles after spaceflights and head-down tilt (HDT) bed rest. While some information is available regarding reconditioning programs on muscle atrophy recovery, the effects on the accumulation of PFC are unknown. Recently, a device (the Functional Re-adaptive Exercise Device—FRED) has been developed which aims to specifically recruit lumbopelvic muscles. This study aimed to investigate the effects of a standard reconditioning (SR) program and SR program supplemented by FRED (SR + FRED) on the recovery of the lumbopelvic muscles following 60-day HDT bed rest. Twenty-four healthy participants arrived at the facility for baseline data collection (BDC) before the bed rest period. They remained in the facility for 13-day post-HDT bed rest and were randomly allocated to one of two reconditioning programs: SR or SR + FRED. Muscle volumes of the lumbar multifidus (LM), lumbar erector spinae (LES), quadratus lumborum (QL), and psoas major (PM) muscles were measured from axial T1-weighted magnetic resonance imaging (MRI) at all lumbar intervertebral disc levels. PFC was determined using a chemical shift-based lipid/water Dixon sequence. Each lumbopelvic muscle was segmented into four equal quartiles (from medial to lateral). MRI of the lumbopelvic region was conducted at BDC, Day-59 of bed rest (HDT59), and Day-13 after reconditioning (R13). Comparing R13 with BDC, the volumes of the LM muscle at L4/L5 and L5/S1, LES at L1/L2, and QL at L3/L4 had not recovered (all—p < 0.05), and the PM muscle remained larger at L1/L2 (p = 0.001). Accumulation of PFC in the LM muscle at the L4/L5 and L5/S1 levels remained higher in the centro-medial regions at R13 than BDC (all—p < 0.05). There was no difference between the two reconditioning programs. A 2-week reconditioning program was insufficient to fully restore all volumes of lumbopelvic muscles and reverse the accumulation of PFC in the muscles measured to BDC values, particularly in the LM muscle at the lower lumbar levels. These findings suggest that more extended reconditioning programs or alternative exercises may be necessary to fully restore the size and properties of the lumbopelvic muscles after prolonged bed rest.

The aim was to identify independent preoperative factors associated with changes in health-related quality of life (HRQoL) following total knee arthroplasty (TKA), and whether these could be used as indicators for surgery. A retrospective study of 3127 TKA patients was undertaken that included 1194 (38.2 ASA grade 3, grade II obesity, a better preoperative EQ-5D or OKS were independently associated with a lesser improvement in HRQoL. The thresholds identified in the EQ-5D or OKS for a clinically significant improvement in HRQoL may be used as potential indicators for referral for TKA. Patella resurfacing was not independently associated with a clinically important improvement in HRQoL. Retrospective diagnostic study, Level III.

Background: A single flywheel exercise countermeasure has been chosen for use on-board the Orion Multi -Purpose Crew Vehicle for spaceflight missions of up to 30 days. As previous missions have typically involved the use of multiple exercise countermeasures there is a concern that the use of only flywheel may lead to boredom and reduce astronaut adherence to exercise prescriptions, presenting a risk to their health and the operational success of the mission. To determine if this will be a concern, this qualitative work identified astronaut-reported operational considerations for the implementation of an exercise countermeasure device for use during spaceflight, and if current plans for the implementation of a single flywheel exercise countermeasure device may affect astronaut adherence to exercise prescriptions.Methods: The responses of three male astronauts to an open-ended qualitative survey were analysed using the-matic analysis. All participants were required to currently be taking part in, or have previously taken part in, human spaceflight.Results: Astronaut preferences for the use of an exercise device during spaceflight were categorised into three broad themes: exercise device ease of access, motivational and behavioural considerations, and operational and technical considerations. The three astronauts considered a single flywheel-based exercise device suitable for use as the sole exercise countermeasure on-board the Orion MPCV, and similar capsular spacecraft, so long as it met several conditions. The device should engage astronauts in a varied exercise prescription. The device should also meet the physiological expectations required of exercise countermeasures for spaceflight deconditioning. The device should be enjoyable to use, and measures should be put in place to reduce boredom (via variety in exercise prescription). The device should be easy to access in terms of both use and setup/takedown. Finally, the device should only be used without other exercise countermeasures for missions of 30 days or less.Conclusion: Individual crewmember preferences should be taken into consideration following crew selection to ensure the greatest adherence to exercise prescriptions. The data reported here should be used to supplement, not entirely inform, the development and use of future exercise countermeasures.

Purpose To examine the time course of recovery for gait and neuromuscular function immediately after and 24-h post interval training. In addition, this study compared the impact of different statistical approaches on detecting changes. Methods Twenty (10F, 10M) healthy, recreational club runners performed a high-intensity interval training (HIIT) session consisting of six repetitions of 800 m. A 6-min medium intensity run was performed pre, post, and 24-h post HIIT to assess hip and knee kinematics and coordination variability. Voluntary activation and twitch force of the quadriceps, along with maximum isometric force were examined pre, post, and 24-h post significance HIIT. The time course of changes were examined using two different statistical approaches: traditional null hypothesis significance tests and “real” changes using minimum detectable change. Results Immediately following the run, there were significant ( P < 0.05) increases in the hip frontal kinematics and coordination variability. The runners also experienced a loss of muscular strength and neuromuscular function immediately post HIIT ( P < 0.05). Individual assessment, however, showed that not all runners experienced fatigue effects immediately post HIIT. Null hypothesis significance testing revealed a lack of recovery in hip frontal kinematics, coordination variability, muscle strength, and neuromuscular function at 24-h post, however, the use of minimum detectable change suggested that most runners had recovered. Conclusion High intensity interval training resulted in altered running kinematics along with central and peripheral decrements in neuromuscular function. Most runners had recovered within 24-h, although a minority still exhibited signs of fatigue. The runners that were not able to recover prior to their run at 24-h were identified to be at an increased risk of running-related injury.

Space agencies are preparing to send humans to the Moon (16% Earth's gravity) and Mars (38% Earth's gravity), however, there is limited evidence regarding the effects of hypogravity on the skeletal system. A novel rodent partial weight-bearing (PWB) model may provide insight into how human bone responds to hypogravity. The aim of this study was to perform a systematic review investigating the effect of PWB on the structure and function of rodent bone. Five online databases were searched with the following inclusion criteria: population (rodents), intervention (PWB for ≥1-week), control (full weight-bearing), outcomes (bone structure/function), and study design (animal intervention). Of the 2,993 studies identified, eight were included. The main findings were that partial weight-bearing exposure for 21-28 days at 20%, 40%, and 70% of full loading causes: (1) loss of bone mineral density, (2) loss of trabecular bone volume, thickness, number, and increased separation, (3) loss of cortical area and thickness, and 4) reduced bone stiffness and strength. These findings predominately relate the tibia/femur of young/mature female mice, however, their deconditioning response appeared similar, but not identical, to male rats. A dose-response trend was frequently observed between the magnitude of deconditioning and PWB level. The deconditioning patterns in PWB resembled those in rodents and humans exposed to microgravity and microgravity analogs. The present findings suggest that countermeasures against bone deconditioning may be required for humans exploring the Lunar and Martian surfaces.