Physical fitness and physical self-concept of male and female young adults in Qatar

Background Physical inactivity is high within the Qatari population, particularly within females, and school-based environments, contributing to increased morbidity and mortality. School-based physical activity (PA) outcomes may be mediated by physical self-concept. Low physical self-concept may negatively impact PA engagement, compromising childhood and adolescent physical fitness, which may translate into adulthood. Normative physical fitness data for the Qatari population is unavailable. Stratifying normative physical fitness appears prudent, to not only allow comparisons to be made worldwide, but enable informed decisions for public health policy and future interventions in the Qatari population.Scopu

The cytokine response to a 30 min downhill run

ISEI Abstract – 7 The cytokine response to a 30 min downhill run L TAYLOR1, CHRISMAS BCR1, CARROLL S2, SMITH A3, PEMBERTON P3, SIEGLER JC4 and MIDGLEY AW5. 1 Applied Sport and Exercise Physiology (ASEP) & Muscle Cellular and Molecular Physiology (MCMP) research groups, Institute of Sport and Physical Activity Research (ISPAR), Department of Sport & Exercise Sciences, University of Bedfordshire, Bedford, UK. 2Department of Sport, Health & Exercise Science, The University of Hull, Hull, UK. 3Department of Clinical Biochemistry, Central Manchester Foundation Trust, Manchester, UK. 4School of Science & Health, University of Western Sydney, Sydney, Australia. 5Department of Sport & Physical Activity, Edge Hill University, Ormskirk, UK. ABSTRACT Eccentric exercise has been ubiquitously shown to result in exericse induced muscle damage (EIMD), accompanied with delayed onset muscle soreness (DOMS). Although eccentric exercise may induce greater neuromuscular adaptation, functional performance may be impaired, and soreness may persist for several days following this type of exercise. This is primarily thought to be due to structural damage to the muscle fibres. In addition to the mechanical theory of EIMD, it has been suggested that an increased inflammatory response may be associated with DOMS. Furthermore, it is possible that the inflammatory response may play a role in mediating recovery, and adaptation following EIMD. However, the effects of EIMD on markers of inflammation have produced inconsistent results. PURPOSE: The main aim of the present study was to investigate the cytokine response to a 30 min downhill run. METHODS: Fifty (36 male, 14 female), apparently healthy participants performed a 30 min downhill run (-12.5%, 70% Vmax). Interleukin 6 (IL-6), high sensitivity C reactive protein (hs-CRP), and tumor necrosis factor alpha (TNF-α) were measured at 1 h, 24 h and 48 h post downhill run. Additionally, isometric maximum voluntary contraction (MVC), and perceived muscle soreness were measured at 24 h and 48 h post downhill run. RESULTS: Detectable levles of TNF-α were only present in three participants, and therefore, these data were excluded from the analysis. There was no significant difference in IL-6 or hs-CRP at any time point (p \u3e 0.10). However, there was a significant decrease in MVC (p ≤ 0.001). On average MVC decreased by 11% and 8% in the dominant and non-dominant leg at 24 h and 48 h respectively. Furthermore, there was a significant increase in muscle soreness (p \u3c 0.001). On average soreness increased by 49 mm and 51 mm 24 h and 48 h post downhill run. CONCLUSION: The significant increase in muscle soreness in the present study is indicative of EIMD. Furthermore, the significant decrement in MVC at 24 h and 48 h post downhill run, demonstrates that neuromuscular function was impaired. The lack of any significant increase in the cytokine response, supports the theory that mechanical damage is the primary mechanism associated with the EIMD and DOMS phenomenon. Nevertheless, when interpreting these results it is important to consider that due to the sampling times employed in the present study, an inflammatory response may have been missed

Pharmacological hypotheses: Is acetaminophen selective in its cyclooxygenase inhibition?

The precise mechanistic action of acetaminophen (ACT; paracetamol) remains debated. ACT’s analgesic and antipyretic actions are attributed to cyclooxygenase (COX) inhibition preventing prostaglandin (PG) synthesis. Two COX isoforms (COX1/2) share 60% sequence structure, yet their functions vary. COX variants have been sequenced among various mammalian species including humans. A COX1 splice variant (often termed COX3) is purported by some as the elusive target of ACT’s mechanism of action. Yet a physiologically functional COX3 isoform has not been sequenced in humans, refuting these claims. ACT may selectively inhibit COX2, with evidence of a 4.4‐fold greater COX2 inhibition than COX1. However, this is markedly lower than other available selective COX2 inhibitors (up to 433‐fold) and tempered by proof of potent COX1 inhibition within intact cells when peroxide tone is low. COX isoform inhibition by ACT may depend on subtle in vivo physiological variations specific to ACT. In vivo ACT efficacy is reliant on intact cells and low peroxide tone while the arachidonic acid concentration state can dictate the COX isoform preferred for PG synthesis. ACT is an effective antipyretic (COX2 preference for PG synthesis) and can reduce afebrile core temperature (likely COX1 preference for PG synthesis). Thus, we suggest with specificity to human in vivo physiology that ACT: (i) does not act on a third COX isoform; (ii) is not selective in its COX inhibition; and (iii) inhibition of COX isoforms are determined by subtle and nuanced physiological variations. Robust research designs are required in humans to objectively confirm these hypotheses

External training loads and smartphone-derived heart rate variability indicate readiness to train in elite soccer

Player readiness can affect the ability to perform and tolerate prescribed training load (TL); therefore, in a time-efficient and practice compatible manner, practitioners need objective evidence to inform readiness to train. Six male professional footballers (mean ± standard deviation [SD]; 26 ± 2 years, 79.0 ± 4.9 kg, 1.82 ± 0.05 m) participated. Heart rate variability (HRV) was recorded using a smartphone application prior to the daily training sessions (247 training sessions [41.17 ± 7.41 per player]). External TL was monitored during training using global positioning system devices. Linear mixed models were used to examine variations in HRV and TL across the study period and to determine relationships between HRV and TL. Differences in TL and HRV were expressed as standardised effect sizes (ES) ± 90% confidence limits. Changes in HRV (outcome) were expressed as the expected change for a 2-SD change in TL (predictor). Across the study period, all external TL measures varied substantially, demonstrating weekly fluctuations in load (ES range = 0.00–7.40). The relationship between morning HRV and external TL ranged from −0.10 for distance and 1.89 for equivalent distance index (EDI). Overall, EDI demonstrated the strongest relationship with morning HRV; therefore, EDI and smartphone-derived HRV may provide an indicator of readiness to train within elite soccer

Reproducibility of creatine kinase: how useful is this measurement tool?

Establishing the reproducibility of a measurement is essential for repeated testing to ensure that any systematic change is a result of an external influence (i.e. intervention), as oppossed to normal random variation. Although some degree of error is inherent in any measure, a measurement tool should yield consistent results that do not fluctuate to an unacceptable degree from one test to another. Creatine kinase (CK) is consistently measured in the blood as a marker of exercise induced muscle damage (EIMD). However, its usefulness as a predictive tool to examine the temporal pattern, and magnitude of muscle damage has been questioned. PURPOSE:The main aim of the present study was to employ a variety of reproducibility statistics in order to examine the typical level of measurement error for CK. METHODS: Fifty (36 male, 14 female), apparently healthy participants completed three trials on three separate occasions with each trial separated by 48 - 72 h. The initial trial served as a familiarisation. During trials 2 and 3 (48 h), CK measures were obtained using standard fingerprick technique, and analysed in duplicate immediatley using a colorimetric assay procedure. Each participant completed their trials at the same time of day, following identical pre-test procedures. RESULTS: The intra-test coefficient of variation (CV) within our laboratory was 9%. Dependent t-tests indicated there was no systematic bias between trials (p = 0.82). The interdian CV displayed low reproducibility (20%). Furthermore, the 95% limits of agreement (LoA) were -69.7 to 63.5 iµ/L. However, the intraclass correlation coefficient (ICC) was 0.90, which can be clasified as displaying ‘high’ reproducibility. CONCLUSION: The interdian CV demonstrates that under identical resting conditions (48 h apart), CK displays inherent low absoulte reproducibility, which may obscure a true experimental effect. However, interpretation of the ICC, suggests that CK has high relative reproducibility. The high range of observed CK values is thought to have increased the size of the correlation. Subsequently, an indivdual change in CK following EIMD may not be indicative of the magnitude of damage, and may simply be a result of the inherent variation (e.g. biological). Therefore, it is advised that caution should be taken when using CK within experimental research, and as an indication of when an athlete has recovered, and is able to recommence training

The influence of environmental and core temperature on cyclooxygenase and PGE2 in healthy humans

Whether cyclooxygenase (COX)/prostaglandin E2 (PGE2) thermoregulatory pathways, observed in rodents, present in humans? Participants (n = 9) were exposed to three environments; cold (20 °C), thermoneutral (30 °C) and hot (40 °C) for 120 min. Core (Tc)/skin temperature and thermal perception were recorded every 15 min, with COX/PGE2 concentrations determined at baseline, 60 and 120 min. Linear mixed models identified differences between and within subjects/conditions. Random coefficient models determined relationships between Tc and COX/PGE2. Tc [mean (range)] increased in hot [+ 0.8 (0.4–1.2) °C; p < 0.0001; effect size (ES): 2.9], decreased in cold [− 0.5 (− 0.8 to − 0.2) °C; p < 0.0001; ES 2.6] and was unchanged in thermoneutral [+ 0.1 (− 0.2 to 0.4) °C; p = 0.3502]. A relationship between COX2/PGE2 in cold (p = 0.0012) and cold/thermoneutral [collapsed, condition and time (p = 0.0243)] was seen, with higher PGE2 associated with higher Tc. A within condition relationship between Tc/PGE2 was observed in thermoneutral (p = 0.0202) and cold/thermoneutral [collapsed, condition and time (p = 0.0079)] but not cold (p = 0.0631). The data suggests a thermogenic response of the COX/PGE2 pathway insufficient to defend Tc in cold. Further human in vivo research which manipulates COX/PGE2 bioavailability and participant acclimation/acclimatization are warranted to elucidate the influence of COX/PGE2 on Tc

Appetite and gut hormone responses to moderate-intensity continuous exercise versus high-intensity interval exercise, in normoxic and hypoxic conditions.

This study investigated the effects of continuous moderate-intensity exercise (MIE) and high-intensity interval exercise (HIIE) in combination with short exposure to hypoxia on appetite and plasma concentrations of acylated ghrelin, peptide YY (PYY), and glucagon-like peptide-1 (GLP-1). Twelve healthy males completed four, 2.6 h trials in a random order: 1) MIE-normoxia, 2) MIE-hypoxia, 3) HIIE-normoxia, and 4) HIIE-hypoxia. Exercise took place in an environmental chamber. During MIE, participants ran for 50 min at 70% of altitude-specific maximal oxygen uptake ( 2max) and during HIIE performed 6 x 3 min running at 90% 2max interspersed with 6 x 3 min active recovery at 50% 2max with a 7 min warm-up and cool-down at 70% 2max (50 min total). In hypoxic trials, exercise was performed at a simulated altitude of 2,980 m (14.5% O2). Exercise was completed after a standardised breakfast. A second meal standardised to 30% of participants’ daily energy requirements was provided 45 min after exercise. Appetite was suppressed more in hypoxia than normoxia during exercise, post-exercise, and for the full 2.6 h trial period (linear mixed modelling, p 0.05). These findings demonstrate that short exposure to hypoxia causes suppressions in appetite and plasma acylated ghrelin concentrations. Furthermore, appetite responses to exercise do not appear to be influenced by exercise modality

The role of acidosis during multiple bouts of high intensity exercise: subsequent effect of recovery in attenuating fatigue

The etiology of fatigue following multiple bouts of high-intensity exercise and the subsequent limitations on exercise performance remains a highly contentious and controversial phenomenon. One important factor that could augment performance is the type of recovery. Therefore, the purpose of this study was to examine the effects of active recovery () vs. passive recovery () on blood acidosis during multiple bouts of forearm-wrist-flexion

Is prostaglandin E2 (PGE2) involved in the thermogenic response to environmental cooling in healthy humans?

Prostaglandin E2 (PGE2) is an eicosanoid derived from cyclooxygenase, an enzyme responsible for the cyclisation and oxygenation of arachidonic acid. In response to bacterial infection, PGE2 binds to EP3 receptors on a population of GABAergic neurons in the pre-optic area. Activation of the EP3 receptor decreases the intracellular cyclic adenosine monophosphate (cAMP) concentrations of these neurons, and the resulting dis-inhibition activates spinal motor outputs responsible for shivering thermogenesis, tachycardia, and brown adipose tissue activation. These involuntary responses increase core body temperature to varying degrees depending on the magnitude of infection; an immune response which is crucial for the survival of the host. However, evidence in animal and human models, primarily through the use of cyclooxygenase inhibitors (which block the production of PGE2), suggests that PGE2 may also be an important molecule for the defence of core temperature against body cooling and cold stress (in the absence of fever). In this paper, evidence within human and animal models is discussed which supports the hypothesis that the eicosanoid PGE2 has a role in maintaining human core temperature during environmental cooling. Given that over-the-counter PGE2 inhibiting drugs [i.e. Non-Steroidal Anti Inflammatory Drugs (NSAIDS)] are frequently used worldwide, it is possible that the use of such medication during environmental cooling could impair one's ability to thermoregulate. Support for such findings could have major implications in the pathology of hypothermia, thus, we suggest that future researchers investigate this specific hypothesis in vivo, using healthy human models. Suggestions for the implementation of such experiments are provided in the present work

Limiting the Rise in Core Temperature During a Rugby Sevens Warm-up With an Ice Vest.

Determine how a cooling vest worn during a warm-up could influence selected performance [counter movement jump (CMJ)], physical (GPS metrics) and psycho-physiological (body temperature and perceptual) variables. In a randomized crossover design, twelve elite male World Rugby Sevens Series athletes completed an outdoor (WBGT: 23-27°C) match-specific externally-valid 30 min warm-up wearing a phase change cooling vest (VEST) and without (CONTROL), on separate occasions 7 days apart. CMJ was assessed before and after the warm-up, with GPS indices and heart rate monitored during the warm-ups, whilst core temperature (Tc; ingestible telemetric pill; n = 6) was recorded throughout the experimental period. Measures of thermal sensation (TS) and comfort (TC) were obtained pre- and post-warm-ups, with rating of perceived exertion (RPE) taken post-warm-ups. Athletes in VEST had a lower ΔTc [mean (SD) VEST 1.3°C (0.1°C); CONTROL 2.0°C (0.2°C)] from pre-warm-up to post-warm-up [effect size (ES) ± 90% confidence limit; -1.54; ±0.62] and Tc peak [mean (SD) VEST 37.8°C (0.3°C); CONTROL 38.5°C (0.3°C)] at the end of the warm-up (-1.59; ±0.64) compared to CONTROL. Athletes in VEST demonstrated a decrease in ΔTS (-1.59; ±0.72) and ΔTC (-1.63; ±0.73) pre- to post-warm-up, with a lower RPE post warm-up (-1.01; ±0.46), compared to CONTROL. Changes in CMJ and GPS indices were trivial between conditions (ES < 0.2). Wearing the vest prior-to and during a warm-up can elicit favorable alterations in physiological (Tc) and perceptual (TS, TC and RPE) warm-up responses, without compromising the utilized warm-up characteristics or physical performance measures