Mohammed Ihsan

Postexercise muscle cooling enhances gene expression of PGC-1α

PURPOSE This study aimed to investigate the influence of localized muscle cooling on postexercise vascular, metabolic, and mitochondrial-related gene expression. METHODS Nine physically active males performed 30 min of continuous running at 70% of their maximal aerobic velocity, followed by intermittent running to exhaustion at 100% maximal aerobic velocity. After exercise, subjects immersed one leg in a cold water bath (10°C, COLD) to the level of their gluteal fold for 15 min. The contralateral leg remained outside the water bath and served as control (CON). Core body temperature was monitored throughout the experiment, whereas muscle biopsies and muscle temperature (Tm) measurements were obtained from the vastus lateralis before exercise (PRE), immediately postexercise (POST-EX, Tm only), immediately after cooling, and 3 h postexercise (POST-3H). RESULTS Exercise significantly increased core body temperature (PRE, 37.1°C ± 0.4°C vs POST-EX, 39.3°C ± 0.5°C, P < 0.001) and Tm in both CON (PRE, 33.9°C ± 0.7°C vs POST-EX, 39.1°C ± 0.5°C) and COLD legs (PRE, 34.2°C ± 0.9°C vs POST-EX, 39.4°C ± 0.3°C), respectively (P < 0.001). After cooling, Tm was significantly lower in COLD (28.9°C ± 2.3°C vs 37.0°C ± 0.8°C, P < 0.001) whereas PGC-1α messenger RNA expression was significantly higher in COLD at POST-3H (P = 0.014). Significant time effects were evident for changes in vascular endothelial growth factor (P = 0.038) and neuronal nitric oxide synthase (P = 0.019) expression. However, no significant condition effects between COLD and CON were evident for changes in both vascular endothelial growth factor and neuronal nitric oxide synthase expressions. CONCLUSIONS These data indicate that an acute postexercise cooling intervention enhances the gene expression of PGC-1α and may therefore provide a valuable strategy to enhance exercise-induced mitochondrial biogenesis.

What are the physiological mechanisms for post-exercise cold water immersion in the recovery from prolonged endurance and intermittent exercise?

Intense training results in numerous physiological perturbations such as muscle damage, hyperthermia, dehydration and glycogen depletion. Insufficient/untimely restoration of these physiological alterations might result in sub-optimal performance during subsequent training sessions, while chronic imbalance between training stress and recovery might lead to overreaching or overtraining syndrome. The use of post-exercise cold water immersion (CWI) is gaining considerable popularity among athletes to minimize fatigue and accelerate post-exercise recovery. CWI, through its primary ability to decrease tissue temperature and blood flow, is purported to facilitate recovery by ameliorating hyperthermia and subsequent alterations to the central nervous system (CNS), reducing cardiovascular strain, removing accumulated muscle metabolic by-products, attenuating exercise-induced muscle damage (EIMD) and improving autonomic nervous system function. The current review aims to provide a comprehensive and detailed examination of the mechanisms underpinning acute and longer term recovery of exercise performance following post-exercise CWI. Understanding the mechanisms will aid practitioners in the application and optimisation of CWI strategies to suit specific recovery needs and consequently improve athletic performance. Much of the literature indicates that the dominant mechanism by which CWI facilitates short term recovery is via ameliorating hyperthermia and consequently CNS mediated fatigue and by reducing cardiovascular strain. In contrast, there is limited evidence to support that CWI might improve acute recovery by facilitating the removal of muscle metabolites. CWI has been shown to augment parasympathetic reactivation following exercise. While CWI-mediated parasympathetic reactivation seems detrimental to high-intensity exercise performance when performed shortly after, it has been shown to be associated with improved longer term physiological recovery and day to day training performances. The efficacy of CWI for attenuating the secondary effects of EIMD seems dependent on the mode of exercise utilised. For instance, CWI application seems to demonstrate limited recovery benefits when EIMD was induced by single-joint eccentrically biased contractions. In contrast, CWI seems more effective in ameliorating effects of EIMD induced by whole body prolonged endurance/intermittent based exercise modalities.

Muscle oxygenation and blood volume reliability during continuous and intermittent running.

The reliability of near infrared spectroscopy derived tissue oxygenation index (TOI) and total haemoglobin concentration (tHb) were examined during continuous (CR) and interval (INT) running. In a repeated measures design, 10 subjects twice performed 30 min of CR at 70% of their peak treadmill velocity, followed by 10 bouts of INT at 100%. Between trial reliability of mean and amplitude changes in TOI and tHb during CR were determined. Muscle de-oxygenation and re-oxygenation rates during INT were calculated using 3 analytical methods; i) linear modelling, ii) minimum and maximum values during work/rest intervals, and iii) mean values during work/rest intervals. Reliability was assessed using coefficient of variation (CV; %). During CR, mean TOI was more reliable (3.5%) compared with TOI amplitude change (34.7%), while mean tHb (12%) was similar to both absolute (9.2%) and relative (10.2%) amplitude changes. During INT, de-oxygenation rates analysed via linear modelling produced the lowest CV (7.2%), while analysis using min-max values produced the lowest CV (9.3%) for re-oxygenation rates. In conclusion, while the variables demonstrated CVs lower than reported changes in training-induced adaptations and/or differences between athletes and controls (23- 450%), practitioners are encouraged to consider the advantages/disadvantages of each method when performing their analysis.

Peripheral blood flow changes in response to postexercise cold water immersion

This study compared the effect of postexercise water immersion (WI) at different temperatures on common femoral artery blood flow (CFA), muscle (total haemoglobin; tHb) and skin perfusion (cutaneous vascular conductance; CVC), assessed by Doppler ultrasound, near‐infrared spectroscopy (NIRS) and laser Doppler flowmetry, respectively. Given that heat stress may influence the vascular response during cooling, nine men cycled for 25 min at the first ventilatory threshold followed by intermittent 30‐s cycling at 90% peak power until exhaustion at 32·8 ± 0·4°C and 32 ± 5% RH. They then received 5‐min WI at 8·6 ± 0·2°C (WI9), 14·6 ± 0·3°C (WI15), 35·0 ± 0·4°C (WI35) or passive rest (CON) in a randomized, crossover manner. Heart rate (HR), mean arterial pressure (MAP), muscle (Tmu), thigh skin (Tthigh), rectal (Tre) and mean body (Tbody) temperatures were assessed. At 60 min postimmersion, decreases in Tre after WI35 (−0·6 ± 0·3°C) and CON (−0·6 ± 0·3°C) were different from WI15 (−1·0 ± 0·3°C; P<0·05), but not from WI9 (−1·0 ± 0·3°C; P = 0·074–0·092). WI9 and WI15 had reduced Tbody, Tthigh and Tmu compared with WI35 and CON (P <0·05). CFA, tHb and CVC were lower in WI9 and WI15 compared with CON (P<0·05). tHb following WI9 remained lower than CON (P = 0·044) at 30 min postimmersion. CVC correlated with tHb during non‐cooling (WI35 and CON) (r2 = 0·532; P<0·001) and cooling recovery (WI9 and WI15) (r2 = 0·19; P = 0·035). WI9 resulted in prolonged reduction in muscle perfusion. This suggests that CWI below 10°C should not be used for short‐term (i.e. <60 min) recovery after exercise.

Reliability of laser Doppler, near-infrared spectroscopy and Doppler ultrasound for peripheral blood flow measurements during and after exercise in the heat

ABSTRACT This study examined the test-retest reliability of near-infrared spectroscopy (NIRS), laser Doppler flowmetry (LDF) and Doppler ultrasound to assess exercise-induced haemodynamics. Nine men completed two identical trials consisting of 25-min submaximal cycling at first ventilatory threshold followed by repeated 30-s bouts of high-intensity (90% of peak power) cycling in 32.8 ± 0.4°C and 32 ± 5% relative humidity (RH). NIRS (tissue oxygenation index [TOI] and total haemoglobin [tHb]) and LDF (perfusion units [PU]) signals were monitored continuously during exercise, and leg blood flow was assessed by Doppler ultrasound at baseline and after exercise. Cutaneous vascular conductance (CVC; PU/mean arterial pressure (MAP)) was expressed as the percentage change from baseline (%CVCBL). Coefficients of variation (CVs) as indicators of absolute reliability were 18.7–28.4%, 20.2–33.1%, 42.5–59.8%, 7.8–12.4% and 22.2–30.3% for PU, CVC, %CVCBL, TOI and tHb, respectively. CVs for these variables improved as exercise continued beyond 10 min. CVs for baseline and post-exercise leg blood flow were 17.8% and 10.5%, respectively. CVs for PU, tHb (r2 = 0.062) and TOI (r2 = 0.002) were not correlated (P > 0.05). Most variables demonstrated CVs lower than the expected changes (35%) induced by training or heat stress; however, minimum of 10 min exercise is recommended for more reliable measurements.

Ergogenic effects of precooling with cold water immersion and ice ingestion: A meta-analysis

Abstract This review evaluated the effects of precooling via cold water immersion (CWI) and ingestion of ice slurry/slushy or crushed ice (ICE) on endurance performance measures (e.g. time-to-exhaustion and time trials) and psychophysiological parameters (core [Tcore] and skin [Tskin] temperatures, whole body sweat [WBS] response, heart rate [HR], thermal sensation [TS], and perceived exertion [RPE]). Twenty-two studies were included in the meta-analysis based on the following criteria: (i) cooling was performed before exercise with ICE or CWI; (ii) exercise longer than 6 min was performed in ambient temperature ≥26°C; and (iii) crossover study design with a non-cooling passive control condition. CWI improved performance measures (weighted average effect size in Hedges’ g [95% confidence interval] + 0.53 [0.28; 0.77]) and resulted in greater increase (ΔEX) in Tskin (+4.15 [3.1; 5.21]) during exercise, while lower peak Tcore (−0.93 [−1.18; −0.67]), WBS (−0.74 [−1.18; −0.3]), and TS (−0.5 [−0.8; −0.19]) were observed without concomitant changes in ΔEX-Tcore (+0.19 [−0.22; 0.6]), peak Tskin (−0.67 [−1.52; 0.18]), peak HR (−0.14 [−0.38; 0.11]), and RPE (−0.14 [−0.39; 0.12]). ICE had no clear effect on performance measures (+0.2 [−0.07; 0.46]) but resulted in greater ΔEX-Tcore (+1.02 [0.59; 1.45]) and ΔEX-Tskin (+0.34 [0.02; 0.67]) without concomitant changes in peak Tcore (−0.1 [−0.48; 0.28]), peak Tskin (+0.1 [−0.22; 0.41]), peak HR (+0.08 [−0.19; 0.35]), WBS (−0.12 [−0.42; 0.18]), TS (−0.2 [−0.49; 0.1]), and RPE (−0.01 [−0.33; 0.31]). From both ergogenic and thermoregulatory perspectives, CWI may be more effective than ICE as a precooling treatment prior to exercise in the heat.

Active and inactive leg hemodynamics during sequential single-leg interval cycling

IntroductionLeg order during sequential single-leg cycling (i.e., exercising both legs independently within a single session) may affect local muscular responses potentially influencing adaptations. This study examined the cardiovascular and skeletal muscle hemodynamic responses during double-leg and sequential single-leg cycling. MethodsTen young healthy adults (28 ± 6 yr) completed six 1-min double-leg intervals interspersed with 1 min of passive recovery and, on a separate occasion, 12 (six with one leg followed by six with the other leg) 1-min single-leg intervals interspersed with 1 min of passive recovery. Oxygen consumption, heart rate, blood pressure, muscle oxygenation, muscle blood volume, and power output were measured throughout each session. ResultsOxygen consumption, heart rate, and power output were not different between sets of single-leg intervals, but the average of both sets was lower than the double-leg intervals. Mean arterial pressure was higher during double-leg compared with sequential single-leg intervals (115 ± 9 vs 104 ± 9 mm Hg, P < 0.05) and higher during the initial compared with second set of single-leg intervals (108 ± 10 vs 101 ± 10 mm Hg, P < 0.05). The increase in muscle blood volume from baseline was similar between the active single leg and the double leg (267 ± 150 vs 214 ± 169 &mgr;M·cm, P = 0.26). The pattern of change in muscle blood volume from the initial to second set of intervals was significantly different (P < 0.05) when the leg was active in the initial (−52.3% ± 111.6%) compared with second set (65.1% ± 152.9%). ConclusionsThese data indicate that the order in which each leg performs sequential single-leg cycling influences the local hemodynamic responses, with the inactive muscle influencing the stimulus experienced by the contralateral leg.

Pre-game perceived wellness highly associates with match running performances during an international field hockey tournament

Abstract This study examined the associations between pre-game wellness and changes in match running performance normalised to either (i) playing time, (ii) post-match RPE or (iii) both playing time and post-match RPE, over the course of a field hockey tournament. Twelve male hockey players were equipped with global positioning system (GPS) units while competing in an international tournament (six matches over 9 days). The following GPS-derived variables, total distance (TD), low-intensity activity (LIA; <15 km/h), high-intensity running (HIR; >15 km/h), high-intensity accelerations (HIACC; >2 m/s2) and decelerations (HIDEC; >−2 m/s2) were acquired and normalised to either (i) playing time, (ii) post-match RPE or (iii) both playing time and post-match RPE. Each morning, players completed ratings on a 0–10 scale for four variables: fatigue, muscle soreness, mood state and sleep quality, with cumulative scores determined as wellness. Associations between match performances and wellness were analysed using Pearson’s correlation coefficient. Combined time and RPE normalisation demonstrated the largest associations with Δwellness compared with time or RPE alone for most variables; TD (r = −0.95; −1.00 to −0.82, p = .004), HIR (r = −0.95; −1.00 to −0.83, p = .003), LIA (r = −0.94; −1.00 to −0.81, p = .026), HIACC (r = −0.87; −1.00 to −0.66, p = .004) and HIDEC (r = −0.90; −0.99 to −0.74, p = .008). These findings support the use of wellness measures as a pre-match tool to assist with managing internal load over the course of a field hockey tournament. Highlights Fixtures during international field hockey tournaments are typically congested and impose high physiological demands on an athlete. To minimise decrements in running performance over the course of a tournament, measures to identify players who have sustained high internal loads are logically warranted. The present study examined the association between changes in simple customised psychometric wellness measures, on changes in match running performance normalised to (i) playing time, (ii) post-match RPE and (iii) playing time and post-match RPE, over the course of a field hockey tournament. Changes in match running performance were better associated to changes in wellness (r = −0.87 to −0.95), when running performances were normalised to both time and RPE compared with time or RPE alone. The present findings support the use of wellness measures as a pre-match tool to assist with managing internal load over the course of a field hockey tournament. Improved associations between wellness scores and match running performances were evident, when running variables were normalised to both playing time and post-match RPE.