Acute physiological responses and muscle recovery in females: a randomised controlled trial of muscle damaging exercise in hypoxia.

BACKGROUND: Studies have investigated the effects of training under hypoxia (HYP) after several weeks in a male population. However, there is still a lack of knowledge on the acute hypoxic effects on physiology and muscle recovery in a female population. METHODS: This randomized-controlled trial aimed to investigate the acute effects of muscle damaging exercise, performed in HYP and normoxia (CON), on physiological responses and recovery characteristics in healthy females. Key inclusion criteria were recreationally active female participants between the age of 18 to 35 years without any previous surgeries and injuries, whilst key exclusion criteria were acute pain situations, pregnancy, and medication intake. The females conducted a muscle-damaging protocol, comprising 5 × 20 drop-jumps, in either HYP (FiO2: 12%) or CON (FiO2: 21%). Physiological responses, including capillary oxygenation (SpO2), muscle oxygenation (SmO2), heart rate (HR), core- (Tcore) and skin- (Tskin) temperature were assessed at the end of each exercise set. Recovery characteristics were quantified by taking venous blood samples (serum creatine-kinase [CK], C-reactive protein [CRP] and blood sedimentation rate [BSR]), assessing muscle swelling of the quadriceps femoris muscle, maximum voluntary isometric contraction (MVIC) of the knee extensor muscles, countermovement jump (CMJ) performance and muscle soreness ratings (DOMS) at 24-, 48- and 72-hrs post-exercise. RESULTS: SpO2 (HYP: 76.7 ± 3.8%, CON: 95.5 ± 1.7%, p < 0.001) and SmO2 (HYP: 60.0 ± 9.3, CON: 73.4 ± 5.8%, p = 0.03) values were lower (p < 0.05) in HYP compared to CON at the end of the exercise-protocol. No physiological differences between HYP and CON were observed for HR, Tcore, and Tskin (all p > 0.05). There were also no differences detected for any recovery variable (CK, CRP, BSR, MVIC, CMJ, and DOMS) during the 72-hrs follow-up period between HYP and CON (all p > 0.05). CONCLUSION: In conclusion, our results showed that muscle damaging exercise under HYP leads to reduced capillary and muscle oxygenation levels compared to normoxia with no difference in inflammatory response and muscle recovery during 72 h post-exercise. TRIAL REGISTRATION: NCT04902924, May 26th 2021.

Cold-water or partial-body cryotherapy? Comparison of physiological responses and recovery following muscle damage.

The aim of this study is to compare (a) the physiological responses following cold-water immersion (CWI) and partial-body cryotherapy (PBC) and (b) the effects on recovery following a muscle-damaging protocol (5 × 20 drop jumps). Nineteen healthy males were randomly allocated into either a CWI (10°C for 10 minutes; n = 9) or a PBC (-60°C for 30 seconds, -135°C for 2 minutes; n = 10) group. The physiological variables (thigh muscle oxygen saturation [SmO2 ], cutaneous vascular conductance [CVC], mean arterial pressure [MAP], and local skin temperature) were assessed immediately prior and up to 60 minutes post-treatment (10-minutes intervals). The recovery variables (thigh muscle swelling, maximum voluntary contraction [MVC] of the right knee extensors, vertical jump performance [VJP], and delayed onset of muscle soreness [DOMS]) were measured immediately prior and up to 72 hours post-treatment (24-hours intervals). Compared to PBC values, CVC (at 30 minutes), SmO2 (at 40 minutes), and lower extremity skin temperature (thigh/shin at 60 minutes) were significantly reduced in the CWI group after the treatment (all P < .05). Only lower extremity skin temperature was significantly reduced in the PBC group directly post-treatment (all P < .05). MAP significantly increased in both groups after the treatments (both P < .05). DOMS did not differ between groups. MVC and VJP returned to baseline in both groups after 24 hours (P > .05). CWI had a greater impact on the physiological response compared to PBC. However, both treatments resulted in similar recovery profiles during a 72-hours follow-up period.

Evaluation and review of body fluids saliva, sweat and tear compared to biochemical hydration assessment markers within blood and urine.

Evaluating and testing hydration status is increasingly requested by rehabilitation, sport, military and performance-related activities. Besides commonly used biochemical hydration assessment markers within blood and urine, which have their advantages and limitations in collection and evaluating hydration status, there are other potential markers present within saliva, sweat or tear. This literature review focuses on body fluids saliva, sweat and tear compared to blood and urine regarding practicality and hydration status influenced by fluid restriction and/or physical activity. The selected articles included healthy subjects, biochemical hydration assessment markers and a well-described (de)hydration procedure. The included studies (n=16) revealed that the setting and the method of collecting respectively accessing body fluids are particularly important aspects to choose the optimal hydration marker. To obtain a sample of saliva is one of the simplest ways to collect body fluids. During exercise and heat exposures, saliva composition might be an effective index but seems to be highly variable. The collection of sweat is a more extensive and time-consuming technique making it more difficult to evaluate dehydration and to make a statement about the hydration status at a particular time. The collection procedure of tear fluid is easy to access and causes very little discomfort to the subject. Tear osmolarity increases with dehydration in parallel to alterations in plasma osmolality and urine-specific gravity. But at the individual level, its sensitivity has to be further determined.

Estimation of sweat rates during cycling exercise by means of the closed chamber condenser technology.

BACKGROUND/AIM: Knowledge of local sweating patterns is of importance in occupational and exercise physiology settings. The recently developed closed chamber condenser technology (Biox Aquaflux® ) allows the measurement of evaporative skin water loss with a greater measurement capacity (up to 1325 g/h/m2 ) compared to traditional evaporimeters. The aim of this study was to evaluate the applicability of the Biox Aquaflux® to estimate sweat production during exercise. METHODS: Fourteen healthy subjects performed a 20-min cycle ergometer trial at respectively 55% heart rate (HRreserve and 75% HRreserve . Sweat production was estimated by measuring body weight before and after exercise, by calculating the amount of sweat collected in a patch, and by measuring the water flux (in g/h/m2 ) with the Biox Aquaflux® instrument. RESULTS: The Biox Aquaflux® instrument allowed the follow up of sweat kinetics at both intensities. Correlations between the measurement methods were all significant for the 75% HRreserve trial (with r ranging from 0.68 to 0.76) whilst for the 55% HRreserve a significant relation was detected between the patch method and the Biox Aquaflux® only (with r ranging from 0.41 to 0.79). CONCLUSION: The Biox Aquaflux® instrument is a practical and direct method for the estimation of local sweat rates under field conditions.

Influence of the timing of ultrasound application on the penetration of corticosteroids.

BACKGROUND: The application of ultrasound to enhance the transdermal transport of drugs is often referred to as 'sonophoresis'. In physiotherapy sonophoresis is applied to the skin through two different procedures: (1) the pre-treatment procedure where the skin is treated with ultrasound irradiation prior to the drug application and (2) a simultaneous treatment mode, where the skin is treated with ultrasound during the application of the pharmacologic substance. The aim of this study was to compare the bioavailability of halcinonide in the stratum corneum comparing the ultrasound pre-treatment vs. the simultaneous treatment method. METHODS: The effect of pre and simultaneous ultrasound treatment (1 MHz, 1 W/cm(2)) was evaluated on the halcinonide blanching response using tristimulus colorimetry 2 h after the initial application. RESULTS: Within the evaluation period, only the ultrasound pre-treatment method resulted in a significant blanching response. CONCLUSION: Timing of the ultrasound application seems to influence the availability and percutaneous penetration process and should be taken into account when estimating the ultrasound enhancing effect.

In vivo measurement of the 3D kinematics of the temporomandibular joint using miniaturized electromagnetic trackers: technical report.

OBJECTIVE: The aim of this study was to evaluate the use of miniaturized electromagnetic trackers (1 × 0.5 × 0.5 cm) fixed on teeth of the maxilla and mandible to analyse in vivo the 3D kinematics of the temporomandibular joint (TMJ). A third sensor was fixed to the forehead, and a fourth sensor was used as a stylus pointer to detect several anatomical landmarks in order to embed a local frame on the cranium. Temporomandibular opening/closing, chewing, laterotrusion and protrusion were examined. RESULTS: The prime objective within this study was to rigidly attach electromagnetic minisensors on teeth. The key for a successful affixation was the kevlar interface. The distances between the two mandibular affixed sensors and between the two maxillar affixed sensors were overall smaller than 0.033 cm for position and 0.2° for attitude throughout the temporomandibular motions. The relative motions between a forehead sensor and the maxilla affixed sensor are too big to suggest a forehead sensor as an alternative for a maxilla affixed sensor. CONCLUSION: The technique using miniaturized electromagnetic trackers furthers on the methods using electromagnetic trackers on external appliances. The method allows full range of motion of the TMJ and does not disturb normal TMJ function.

The influence of stratum corneum hydration on body fat determination by bioelectrical impedance analysis.

BACKGROUND/AIMS: Bioelectrical impedance analysis (BIA) is used for the estimation of the amount of body fat. We evaluated the influence of the stratum corneum hydration at the contact areas used for BIA on the body fat estimation. METHODS: Stratum corneum hydration was measured at the sole of the right foot and the palm of the right hand before and after contact with the Tanita Body Composition Analyzer TBF 410(®) and the Omron Body Fat Analyzer(®) , (n=128 females and 126 males), respectively. Changes in stratum corneum hydration during the contact time were calculated (ΔHYD). As a gold standard for body fat estimation, the underwater weighing method (UWW) was used and the deviation of this standard was calculated for the Tanita (DT) and the Omron (DO) measurement. RESULTS: During contact with the Tanita, stratum corneum hydration increased significantly at the foot. Neither stratum corneum hydration measured at the respective contact sites before BIA nor ΔHYD at the respective skin sites was related to DT or with DO. CONCLUSION: The BIA measuring procedure using the Tanita instrument leads to an occlusive effect at the contact site. BIA for the determination of body composition is not influenced by stratum corneum hydration.