Heat stress impairs proprioception but not running mechanics

ObjectivesTo determine the effects of heat stress on ankle proprioception and running gait pattern.DesignCounterbalanced repeated measures.Methods12 trained runners performed a proprioception test (active movement discrimination) before and immediately after a 30 min, self-paced treadmill run in HOT (39 °C) and COOL (22 °C) ambient conditions. Velocity was imposed during the first and last minute (70% of maximal aerobic velocity, 13.3 ± 0.8 km h⁻¹) for determination of running mechanics and spring–mass characteristics.ResultsRectal (39.7 ± 0.4 vs. 39.4 ± 0.4 °C), skin (36.3 ± 1.1 vs. 31.8 ± 1.1 °C) and average body (38.3 ± 0.2 vs. 36.4 ± 0.4 °C) temperatures together with heart rate (178 ± 8 vs. 174 ± 6 bpm) and thermal discomfort (6.5 ± 0.5 vs. 4.3 ± 1.3) were all higher at the end of the HOT compared to COOL run (all p < 0.05). Distance covered was lower in HOT than COOL (−5.1 ± 3.6%, p < 0.001). Average error during the proprioception test increased after running in HOT (+11%, p < 0.05) but not in COOL (−2%). There was no significant difference for most segmental and joint angles at heel contact, except for a global increase in pelvis retroversion and decrease in ankle dorsi-flexion angles with time (p < 0.05). Step frequency decreased (−2.5 ± 3.6%) and step length increased (+2.6 ± 3.8%) over time (p < 0.05), independently of condition. Spring–mass characteristics remained unchanged (all p > 0.05).ConclusionsHeat stress exacerbates thermal, cardiovascular and perceptual responses, while running velocity was slower during a 30 min self-paced treadmill run. Heat stress also impairs ankle proprioception during an active movement discrimination task, but it has no influence on gait pattern assessed at a constant, sub-maximal velocity.     

Does exertional heat stress impact gastrointestinal function and symptoms?

ObjectivesExertional-heat stress generates a thermoregulatory strain that exacerbates splanchnic hypoperfusion and sympathetic drive, but the effects on gastrointestinal function are poorly defined. The study aimed to determine the effects of exertional-heat stress on gastric myoelectrical activity, orocecal transit time (OCTT), and gastrointestinal symptoms (GIS).DesignRandomised cross-over study.MethodsEndurance runners (n = 16) completed 2 h of running at 60 % V?O_2max in 35 °C (HOT) and 22 °C (TEMP) ambient conditions. Surface electrogastrography (cEGG) was recorded pre- and post-exercise to determine gastric myoelectrical activity, a lactulose challenge was used to determine OCTT, and GIS were recorded using a modified visual analogue scale tool.ResultsPost-exercise T_re [HOT:38.8(38.5 to 39.0)°C and TEMP:38.1(37.8 to 38.4)°C] and Δ T_re [HOT:2.2(2.0 to 2.4)°C and TEMP:1.5(1.2 to 1.8)°C] was higher on HOT compared to TEMP (p < 0.001). Normal gastric myoelectrical cycle frequency reduced (p = 0.010) on HOT [? 11.7(? 20.8 to ? 2.6)%], but this decrease did not differ (p = 0.058) from TEMP [? 2.7(? 8.3 to 3.0)%]. Bradygastria increased post-exercise on both trials (HOT:11.3(2.3 to 20.4)%, p = 0.030; and TEMP:7.4(2.1 to 12.6)%, p = 0.009). OCTT did not differ between trials (p = 0.864) with transit response classified as very slow on both HOT (99(68 to 131)min) and TEMP (98(74 to 121)min). GIS incidence was higher on HOT (88 %) compared to TEMP (81 %), in accordance with greater total-GIS and upper-GIS severity (p = 0.005 and p = 0.033, respectively).ConclusionsRunning for 2 h at 60 % V?O_2max in either hot or temperate ambient conditions instigates perturbations in myoelectrical activity and OCTT, with GIS incidence and severity greater in hot conditions.     

Optimal cooling strategies for players in Australian Tennis Open conditions

Objectives

We compared the utility of four cooling interventions for reducing heat strain during simulated tennis match-play in an environment representative of the peak conditions possible at the Australian Open (45 °C, <10% RH, 475 W/m² solar radiation).

Progressive hyperthermia elicits distinct responses in maximum and rapid torque production

ObjectivesTo investigate the effect of progressive whole-body hyperthermia on maximal, and rapid voluntary torque production, and their neuromuscular determinants.DesignRepeated measures, randomised.MethodsNine participants performed sets of neuromuscular assessments in HOT conditions (∼50 °C, ∼35% relative humidity) at rectal temperatures (T_re) of 37, 38.5 and 39.5 °C and in CON conditions (∼22 °C, ∼35% relative humidity) at a T_re of ∼37 °C and pre-determined comparative time-points. Electrically evoked twitch (single impulse) and octet (8 impulses at 300 Hz) responses were measured at rest. Maximum voluntary torque (MVT), surface electromyography (EMG) normalised to maximal M-wave, and voluntary activation (VA) were measured during 3−5 s isometric maximal voluntary contractions. Rate of torque development (RTD) and normalised EMG were measured during rapid voluntary isometric contractions from rest.ResultsAll neuromuscular variables were unaffected by time in CON. In HOT, MVT, normalised EMG at MVT and VA were lower at 39.5 °C compared to 37 °C (p < 0.05). Early- (0−50 ms) and middle- (50−100 ms) phase voluntary RTD were unaffected by increased T_re (p > 0.05), despite lower normalised EMG at T_re 39.5 °C (p < 0.05) in rapid contractions. In contrast, late-phase (100−150 ms) voluntary RTD was lower at 38.5 °C and 39.5 °C compared to 37 °C (p < 0.05) in HOT. Evoked twitch and octet RTD increased with increased T_re (p < 0.05).ConclusionsHyperthermia reduced late-phase voluntary RTD, likely due to reduced neural drive and the reduction in MVT. In contrast, early- and middle-phase voluntary RTD were unaffected by hyperthermia, likely due to the conflicting effects of reduced neural drive but faster intrinsic contractile properties.     

Thermoregulatory responses to ice slurry ingestion during low and moderate intensity exercises with restrictive heat loss

ObjectivesWe investigated the thermoregulatory responses to ice slurry ingestion during low- and moderate-intensity exercises with restrictive heat loss.DesignRandomised, counterbalanced, cross-over design.MethodsFollowing a familiarisation trial, ten physically active males exercised on a motorised treadmill at low-intensity (L; 40% VO_2max) or moderate-intensity (M; 70% VO_2max) for 75-min, in four randomised, counterbalanced trials. Throughout the exercise bout, participants donned a raincoat to restrict heat loss. Participants ingested 2 g kg^?1 body mass of ambient water (L + AMB and M + AMB trials) or ice slurry (L + ICE and M + ICE trials) at 15-min intervals during exercise in environmental conditions of T_db, 25.1 ± 0.6 °C and RH, 63 ± 5%. Heart rate (HR), gastrointestinal temperature (T_gi), mean weighted skin temperature (T_sk), estimated sweat loss, ratings of perceived exertion (RPE) and thermal sensation (RTS) were recorded.ResultsCompared to L + AMB, participants completed L + ICE trials with lower ΔT_gi (0.8 ± 0.3°C vs 0.6 ± 0.2 °C; p = 0.03), mean RPE (10 ± 1 vs 9 ± 1; p = 0.03) and estimated sweat loss (0.91 ± 0.2 L vs 0.78 ± 0.27 L; p = 0.04). Contrastingly, T_gi (p = 0.22), T_sk (p = 0.37), HR (p = 0.31), RPE (p = 0.38) and sweat loss (p = 0.17) were similar between M + AMB and M + ICE trials. RTS was similar during both low-intensity (4.9 ± 0.5 vs 4.7 ± 0.3; p = 0.10) and moderate-intensity exercise (5.3 ± 0.47 vs 5.0 ± 0.4; p = 0.09).ConclusionsPer-cooling using ice slurry ingestion marginally reduced thermal strain during low-intensity but not during moderate-intensity exercise. Ice slurry may be an effective and practical heat mitigation strategy during low-intensity exercise such as in occupational and military settings, but a greater volume should be considered to ensure its efficacy.     

The influence of passive heat maintenance on lower body power output and repeated sprint performance in professional rugby league players

Objectives: The pre-competition warm-up mediates many temperature related physiological changes which generally lead to an improvement in performance. However, after ceasing exercise body temperature declines rapidly, which reduces some of the benefits of the initial warm-up. We examined the effects of a passive heat maintenance strategy on post-warm-up core temperature (T_core) and performance in professional rugby league players. Design: Twenty professional rugby league players completed this randomised and counter-balanced study. Methods: After a standardised warm-up, players completed a countermovement jump (CMJ) before resting for 15 min wearing normal training attire (control) or wearing a passive heat maintenance jacket (PHM), players then completed another CMJ and a repeated sprint protocol (RSA). T_core was measured at baseline, post-warm-up, pre-RSA and post-RSA. CMJ were analysed for peak power output (PPO), and RSA for fastest, mean and total sprint time. Results: Post-warm-up T_core (mean ± SD; control 37.70 ± 0.28; PHM 37.70 ± 0.27 °C; p = 0.741) and PPO (control 5220 ± 353 vs. PHM 5213 ± 331 W; p = 0.686) were similar between conditions. At pre-RSA, PHM was associated with greater T_core (control 37.14 ± 0.31 vs. PHM 37.51 ± 0.30 °C; p < 0.001) and PPO (control 4868 ± 345 vs. PHM 5056 ± 344 W; p < 0.001) when compared to control. The decline in PPO from post-warm-up to pre-RSA was related to the drop in T_core (r = 0.71; p < 0.001). During the RSA, fastest, mean and total sprint time were all improved under PHM compared to control (p < 0.05). Conclusions: Passive heat maintenance is an effective method of attenuating the post-warm-up decline in T_core and improves PPO and repeated sprint ability in professional rugby league players.     

Does the temperature of water ingested during exertional-heat stress influence gastrointestinal injury,symptoms, and systemic inflammatory profile?

Objectives

The study aimed to determine the effects of temperature of ingested water during exertional-heat stress on gastrointestinal injury, symptoms and systemic inflammatory responses.

Extended post-exercise hyperthermia in athletes with a spinal cord injury

ObjectivesDetermine the extent and underlying causes of post-exercise hyperthermia in athletes with a spinal cord injury following exercise.DesignObservational.MethodsThirty-one males (8 with tetraplegia [TP; C5-C8], 7 with high paraplegia [HP; T1-T5], 8 with low paraplegia [LP; T6-L1] and 8 able-bodied [AB]), recovered in 35 °C/50%RH for 45 min after 30-min of exercise at a metabolic heat production (H_prod) of 4.0 W/kg (AB vs TP) or 6.0 W/kg (AB vs HP vs LP). Esophageal (T_es), gastrointestinal (T_gi) and skin temperatures, H_prod, local sweat rate (LSR) and mean arterial pressure were measured.ResultsTP maintained a higher T_es (38.05 °C [95% CI: 37.83 °C, 38.28 °C], AB: 36.77 °C [36.56 °C, 36.98 °C], p < 0.001) and T_gi (TP: 38.36 °C [38.15 °C, 38.58 °C], AB: 37.26 °C [37.04 °C, 37.47 °C], p < 0.001), with peak values observed 45 min post-exercise. Core temperatures all declined in HP, LP and AB, but HP maintained a higher T_es than AB (p = 0.030), and higher T_gi than LP and AB (p = 0.019). No differences in post-exercise H_prod were observed between TP and AB (p = 0.264), or HP, LP and AB (p = 0.124). Evaporative heat loss was estimated to be zero in TP, while back LSR was greater in HP than LP (p = 0.009). Minimal dry heat loss occurred in SCI groups (TP: 9 W/m² [6, 12], HP: 4 W/m² [1, 6], LP: 2 W/m² [0, 5]).ConclusionsSubstantial post-exercise hyperthermia is evident in TP (∼1.4 °C hotter than AB after 45 min of post-exercise recovery) due to minimal evaporation. HP have delayed post-exercise thermoregulatory recovery whereas LP respond similarly to AB.     

Influence of post-warm-up recovery time on swim performance in international swimmers

ObjectivesSwimmers must enter a marshalling call-room 20 min prior to racing, which results in some swimmers completing their warm-up 45 min pre-race. Since a recovery period longer than 15–20 min may prove problematic, this study examined 200 m freestyle performance after a 20 and 45 min post-warm-up recovery period.DesignEight international swimmers completed this randomised and counter-balanced study.MethodsAfter a standardised warm-up, swimmers rested for either 20 (20 min) or 45 min (45 min) prior to completing a 200 m freestyle time-trial (TT). Core temperature (T_core), blood lactate (BL), heart rate and rate of perceived exertion (RPE) were recorded at baseline, post-warm-up, pre-TT, immediately post-TT and at 3 min post-TT.ResultsT_core was similar after the warm-up under both conditions, however, at pre-TT T_core was greater under 20 min (mean ± SD; 20 min 37.8 ± 0.2 vs. 45 min 37.5 ± 0.2 °C; P = 0.002). BL was similar between conditions at all-time points before the TT (P > 0.05). Swimmers demonstrated a 1.5 ± 1.1% improvement in performance under 20 min (20 min 125.74 ± 3.64 vs. 45 min 127.60 ± 3.55 s; P = 0.01). T_core was similar between conditions at immediately post-TT and 3 min post-TT (P > 0.05), however, BL was higher at these time points under 20 min (P < 0.05). Heart rate and RPE were similar between conditions at all-time points (P > 0.05).Conclusions200 m freestyle performance is faster 20 min post-warm-up when compared to 45 min probably due to better T_core maintenance. This has implications for swim race preparation as warm-up procedures should be completed close to entering the pre-race call room, in order to maintain elevated core temperature.     

Aluminium salt-based antiperspirant coated prosthesis liners do not suppress local sweating during moderate intensity exercise in hot and temperate conditions

ObjectiveTo determine whether coating prosthesis liners with a 5% aluminium zirconium tetrachlorohydrate antiperspirant solution (AZCH) reduces local sweating on the thigh.DesignDouble-blinded counter-balanced crossover designMethodsFourteen able-bodied participants (age: 28 ± 5 y; body mass: 73.9 ± 7.9 kg, height: 1.73 ± 0.09 m; peak oxygen consumption [VO_2peak]: 50.7 ± 9.1 mlO₂⋅ kg⁻¹⋅ min⁻¹) simultaneously wore a prosthesis liner on each leg, one treated with AZCH and one untreated, for four days prior to running at 50% of VO_2peak for 60 min in a temperate (23.7 ± 0.7 °C and 42.2 ± 2.6% relative humidity) or hot (34.0 ± 1.6 °C and 40.8 ± 6.1% relative humidity) environment. Rectal temperature (T_re) and whole-body sweat rates (WBSR) were measured to characterize thermal strain. Local sweat rate (LSR) was measured bilaterally underneath the liners, continuously, and heat-activated-sweat gland density (HASGD) was measured bilaterally every 15 min.ResultsIn temperate condition, the mean change in T_re was 1.2±0.4 °C and WBSR was 723 ± 129 g⋅ h⁻¹, whereas in the hot condition, change in T_re was 1.2±0.5 °C and WBSR was 911 ± 231 g⋅ h⁻¹. In the temperate condition, AZCH treatment did not alter LSR (treated: 0.50±0.17 mg·cm^–2 min^–1, untreated: 0.50±0.17 mg·cm^–2 min^–1; P = 0.87) or HASGD (treated: 54±14 glands·cm^–2, untreated 55±14 glands·cm^–2; P = 0.38). In the hot condition, AZCH treatment paradoxically increased LSR (treated: 0.88 ± 0.38 mg·cm^–2 min^–1, untreated: 0.74 ± 0.28 mg·cm^–2 min^–1; P = 0.04) but not HASGD (treated: 52 ± 17 glands·cm^–2, untreated: 48 ± 19 glands·cm^–2; P = 0.77).ConclusionThese results indicate coating prosthesis liners with 5% AZCH is ineffective at reducing local sweating.     

The effects of multidirectional soccer-specific fatigue on markers of hamstring injury risk

The purpose of this work was to investigate the effect of multidirectional soccer-specific fatigue on hamstring muscle strength and angle of peak torque. Sixteen male semi-professional soccer players (mean ± S.D.: age: 21.3 ± 2.9 years; height 185.0 ± 8.7 cm; body mass 81.6 ± 6.7 kg) completed the SAFT⁹⁰, a multidirectional, intermittent 90-min exercise protocol based on data from English Championship soccer matches. Prior to exercise (t₀), at half-time (t₄₅) and post-exercise (t₁₀₅), subjects performed three maximal dominant limb isokinetic contractions (Biodex, System 3) at 120° s^?1 through a 90° range for concentric and eccentric knee flexors and concentric knee extensors. Analysis of variance revealed significant time dependant reductions in gravity corrected eccentric hamstring peak torque, and consequently in the functional hamstring:quadriceps ratio (P < 0.01). Eccentric hamstring peak torque decreased significantly during each half (t₀: 272.0 ± 43.2; t₄₅: 240.4 ± 43.3; t₁₀₅: 226.3 ± 45.7 N m). The functional hamstring:quadriceps ratio also decreased significantly during each half (t₀: 116.6 ± 21.2; t₄₅: 107.1 ± 17.6; t₁₀₅: 98.8 ± 20.3%). There were no significant changes in concentric hamstring or quadriceps peak torque observed during SAFT⁹⁰ (P > 0.05). Data analysis also revealed significant differences for Angle of Peak Torque for eccentric hamstrings (P < 0.05) which was significantly higher at the end of each half (t₄₅: 37 ± 15; t₁₀₅: 38 ± 18°) than the pre-exercise value (t₀: 28 ± 12°). There was a time dependant decrease in peak eccentric hamstring torque and in the functional strength ratio which may have implications for the increased predisposition to hamstring strain injury during the latter stages of match-play.     

Short term heat acclimation reduces heat strain during a first,but not second,consecutive exercise-heat exposure

ObjectivesDetermine whether five days of heat acclimation reduces cardiovascular and thermoregulatory strain during consecutive exercise-heat exposures on the sixth day in the heat.DesignPair-matched randomized control trial.MethodsTwenty-four males completed two, 120 min exercise sessions (Session 1, Session 2) in a single day before (Day 1) and after (Day 6) four additional days of exercise in either hot (HOT: 40 °C, 40% relative humidity, n = 16) or temperate (CON: 23 °C, 25% relative humidity, n = 8) environments. A mixed-methods heat acclimation approach was implemented. Day 2 consisted of 120 min of moderate-high intensity treadmill exercise. Days 3–5 consisted of 90 min of moderate-high intensity exercise, with HOT completing this in a hyperthermia clamped manner at rectal temperature ≥38.5 °C, and CON < 38.5 °C.ResultsSession 1 end of exercise rectal temperature and heart rate were lower on Day 6 compared to Day 1 for HOT (p = 0.012, p = 0.003) but not CON (p = 0.152, p = 0.437). Session 2 end of exercise rectal temperature was not different between days for HOT (p = 0.104) or CON (p = 0.275). Session 2 end of exercise heart rate was lower on Day 6 compared to Day 1 for HOT (p = 0.004) and CON (p = 0.039). Session 1 sweat sensitivity was greater on Day 6 compared to Day 1 for HOT (p = 0.039) but not CON (p = 0.257). Sweat rate was unchanged for HOT and CON between days during Session 1 (p = 0.184, p = 0.962) and Session 2 (p = 0.051, p = 0.793), respectively.ConclusionsFive days of heat acclimation reduced cardiovascular strain but not thermoregulatory strain during the second, consecutive exercise-heat exposure.ClinicalTrials.gov IdentifierNCT04053465.     

Self-paced exercise performance in the heat with neck cooling,menthol application,and abdominal cooling

Objectives

To investigate whether the exercise performance benefits with neck cooling in the heat are attributable to neck-specific cooling, general body cooling, a cooler site-specific thermal perception or a combination of the above.

Fibular taping does not influence ankle dorsiflexion range of motion or balance measures in individuals with chronic ankle instability

ObjectivesTo determine the effects of fibular taping on ankle dorsiflexion range of motion (ROM) and dynamic balance in individuals with chronic ankle instability (CAI).DesignSingle-blind, randomized crossover.MethodsTwenty-three individuals (age = 23.4 ± 2.5 years, height = 171.6 ± 12.4 cm, mass = 71.5 ± 13.1 kg) with CAI were allocated to either a fibular taping intervention or sham taping intervention (tape applied without tension) over the course of two visits. Weight-bearing ankle dorsiflexion ROM and components of the Star Excursion Balance Test (SEBT) were measured before and after intervention.ResultsThere was not a significant change in ankle dorsiflexion ROM when comparing the taping interventions (F_1,43 = 1.03, P = .32), but both interventions resulted in a small increase (F_1,43 = 8.07, P = .007) in dorsiflexion ROM (pre = 36.7° ± 6.9°, post = 37.7° ± 6.2°). This increase in ROM did not exceed the established minimal detectable change for dorsiflexion ROM. Fibular taping with tension produced an increase (F_1,41 = 5.84, P = .02) (pre = 69.0 ± 9.1%, post = 70.6 ± 8.6%) in posterolateral reach distance when compared to taping without tension (pre = 72.7 ± 11.0%, post = 71.4 ± 9.6%), but this increase did not exceed the established minimal detectable change. There was not a significant change in dynamic balance between groups for the anterior (F_1,41 = 2.33, P = .14) and posteromedial (F_1,41 = .41, P = .53) reach directions.ConclusionsAlthough small changes in ankle dorsiflexion ROM and posterolateral reach distances were observed, these changes did not exceed established minimal detectable change values for these measures. These results suggest that the benefits of fibular taping are not related to an increase in ankle dorsiflexion ROM or dynamic balance.     

Femoral torsion assessment with MRI in children: Should we use the bony or cartilaginous contours?

ObjectiveTo assess whether the use of cartilaginous contours at the femoral condyles instead of bony contours significantly changes femoral torsion measurements in children.Materials and MethodsFemoral torsion was measured in 32 girls (mean age 10.1 years ± 2.3 standard deviation) and 42 boys (10.9 years ± 2.5) on axial magnetic resonance (MR) images by two independent readers (R1,R2). The femoral condyle angle was measured using each the cartilaginous and bony contours of the distal femur. Cartilage thickness at femoral condyles was assessed. Intraclass-correlation-coefficient (ICC) and Pearson's correlation were used for statistical analysis.ResultsMean difference between cartilaginous and bony femoral torsion in girls was −1.1° ± 1.75 (range, −5.4° to 3.1°) for R1 and −1.64° ± 1.67 (−6.3° to 2.1°) for R2, in boys −1.5° ± 1.87 (−8.4° to 1.1°) for R1 and −2.28° ± 1.48 (−4.3° to 9.7°) for R2. Weak-to-moderate correlations between difference of cartilaginous-versus-bony measurements and cartilage thickness (r = −0.15 to −0.55, P < 0.001–0.46) or age (r = −0.33 to 0.46, P < 0.001–0.006) were found for both genders. Intermethod-ICC for cartilaginous versus bony femoral torsion measurements was 0.99/0.99 for R1/R2 in girls, and 0.99/0.98 in boys.ConclusionThere is only a small difference when measuring femoral torsion through cartilaginous versus bony contours, and no major difference in this between boys and girls.     

Prescribing joint co-ordinates during model preparation in OpenSim improves lower limb unplanned sidestepping kinematics

ObjectivesInvestigate how prescribing participant-specific joint co-ordinates during model preparation influences the measurement agreement of inverse kinematic (IK) derived unplanned sidestepping (UnSS) lower limb kinematics in OpenSim in comparison to an established direct kinematic (DK) model.DesignParallel forms repeatability.MethodsThe lower limb UnSS kinematics of 20 elite female athletes were calculated using: 1) an established DK model (criterion) and, 2) two IK models; one with (IK_PC) and one without (IK₀) participant-specific joint co-ordinates prescribed during the marker registration phase of model preparation in OpenSim. Time-varying kinematic analyses were performed using one dimensional (1D) statistical parametric mapping (α = 0.05), where zero dimensional (0D) Root Mean Squared Error (RMSE) estimates were calculated and used as a surrogate effect size estimates.ResultsStatistical differences were observed between the IK_PC and DK derived kinematics as well as the IK₀ and DK derived kinematics. For the IK_PC and DK models, mean kinematic differences over stance for the three dimensional (3D) hip joint, 3D knee joint and ankle flexion/extension (F/E) degrees of freedom (DoF) were 46 ± 40% (RMSE = 5 ± 5°), 56 ± 31% (RMSE = 7 ± 4°) and 3% (RMSE = 2°) respectively. For the IK₀ and DK models, mean kinematics differences over stance for the 3D hip joint, 3D knee joint and ankle F/E DoF were 70 ± 53% (RMSE = 14 ± 11°), 46 ± 48% (RMSE = 8 ± 7°) and 100% (RMSE = 11°) respectively.ConclusionsPrescribing participant-specific joint co-ordinates during model preparation improves the agreement of IK derived lower limb UnSS kinematics in OpenSim with an established DK model, as well as previously published in-vivo knee kinematic estimates.     

Dietary supplementation with New Zealand blackcurrant extract enhances fat oxidation during submaximal exercise in the heat

ObjectivesThis study investigated the effect of 7 days’ supplementation with New Zealand blackcurrant extract on thermoregulation and substrate metabolism during running in the heat.DesignRandomized, double-blind, cross-over study.MethodsTwelve men and six women (mean ± SD: Age 27 ± 6 years, height 1.76 ± 0.10 m, mass 74 ± 12 kg, V̇O_2max 53.4 ± 7.0 mL kg⁻¹ min⁻¹) completed one assessment of maximal aerobic capacity and one familiarisation trial (18 °C, 40% relative humidity, RH), before ingesting 2 × 300 mg day⁻¹ capsules of CurraNZ™ (each containing 105 mg anthocyanin) or a visually matched placebo (2 × 300 mg microcrystalline cellulose M102) for 7 days (washout 14 days). On day 7 of each supplementation period, participants completed 60 min of fasted running at 65% V̇O_2max in hot ambient conditions (34 °C and 40% relative humidity).ResultsCarbohydrate oxidation was decreased in the NZBC trial [by 0.24 g min⁻¹ (95% CI: 0.21–0.27 g min^-1)] compared to placebo (p =  0.014, d = 0.46), and fat oxidation was increased in the NZBC trial [by 0.12 g min⁻¹ (95% CI: 0.10 to 0.15 g min⁻¹)], compared to placebo (p = 0.008, d = 0.57). NZBC did not influence heart rate (p = 0.963), rectal temperature (p = 0.380), skin temperature (p = 0.955), body temperature (p = 0.214) or physiological strain index (p = 0.705) during exercise.ConclusionsSeven-days intake of 600 mg NZBC extract increased fat oxidation without influencing cardiorespiratory or thermoregulatory variables during prolonged moderate intensity running in hot conditions.