Charles D Thake

Water and sodium intake habits and status of ultra-endurance runners during a multi-stage ultra-marathon conducted in a hot ambient environment: an observational field based study

BackgroundAnecdotal evidence suggests ultra-runners may not be consuming sufficient water through foods and fluids to maintenance euhydration, and present sub-optimal sodium intakes, throughout multi-stage ultra-marathon (MSUM) competitions in the heat. Subsequently, the aims were primarily to assess water and sodium intake habits of recreational ultra-runners during a five stage 225 km semi self-sufficient MSUM conducted in a hot ambient environment (Tmax range: 32°C to 40°C); simultaneously to monitor serum sodium concentration, and hydration status using multiple hydration assessment techniques.MethodsTotal daily, pre-stage, during running, and post-stage water and sodium ingestion of ultra-endurance runners (UER, n = 74) and control (CON, n = 12) through foods and fluids were recorded on Stages 1 to 4 by trained dietetic researchers using dietary recall interview technique, and analysed through dietary analysis software. Body mass (BM), hydration status, and serum sodium concentration were determined pre- and post-Stages 1 to 5.ResultsWater (overall mean (SD): total daily 7.7 (1.5) L/day, during running 732 (183) ml/h) and sodium (total daily 3.9 (1.3) g/day, during running 270 (151) mg/L) ingestion did not differ between stages in UER (p < 0.001 vs. CON). Exercise-induced BM loss was 2.4 (1.2)% (p < 0.001). Pre- to post-stage BM gains were observed in 26% of UER along competition. Pre- and post-stage plasma osmolality remained within normal clinical reference range (280 to 303 mOsmol/kg) in the majority of UER (p > 0.05 vs. CON pre-stage). Asymptomatic hyponatraemia (<135 mmol/L) was evident pre- and post-stage in n = 8 UER, corresponding to 42% of sampled participants. Pre- and post-stage urine colour, urine osmolality and urine/plasma osmolality ratio increased (p < 0.001) as competition progressed in UER, with no change in CON. Plasma volume and extra-cellular water increased (p < 0.001) 22.8% and 9.2%, respectively, from pre-Stage 1 to 5 in UER, with no change in CON.ConclusionWater intake habits of ultra-runners during MSUM conducted in hot ambient conditions appear to be sufficient to maintain baseline euhydration levels. However, fluid over-consumption behaviours were evident along competition, irrespective of running speed and gender. Normonatraemia was observed in the majority of ultra-runners throughout MSUM, despite sodium ingestion under benchmark recommendations.

Cross Acclimation between Heat and Hypoxia: Heat Acclimation Improves Cellular Tolerance and Exercise Performance in Acute Normobaric Hypoxia

Background: The potential for cross acclimation between environmental stressors is not well understood. Thus, the aim of this investigation was to determine the effect of fixed-workload heat or hypoxic acclimation on cellular, physiological, and performance responses during post acclimation hypoxic exercise in humans. Method: Twenty-one males (age 22 ± 5 years; stature 1.76 ± 0.07 m; mass 71.8 ± 7.9 kg; V˙O2 peak 51 ± 7 mL.kg−1.min−1) completed a cycling hypoxic stress test (HST) and self-paced 16.1 km time trial (TT) before (HST1, TT1), and after (HST2, TT2) a series of 10 daily 60 min training sessions (50% N V˙O2 peak) in control (CON, n = 7; 18°C, 35% RH), hypoxic (HYP, n = 7; fraction of inspired oxygen = 0.14, 18°C, 35% RH), or hot (HOT, n = 7; 40°C, 25% RH) conditions. Results: TT performance in hypoxia was improved following both acclimation treatments, HYP (−3:16 ± 3:10 min:s; p = 0.0006) and HOT (−2:02 ± 1:02 min:s; p = 0.005), but unchanged after CON (+0:31 ± 1:42 min:s). Resting monocyte heat shock protein 72 (mHSP72) increased prior to HST2 in HOT (62 ± 46%) and HYP (58 ± 52%), but was unchanged after CON (9 ± 46%), leading to an attenuated mHSP72 response to hypoxic exercise in HOT and HYP HST2 compared to HST1 (p < 0.01). Changes in extracellular hypoxia-inducible factor 1-α followed a similar pattern to those of mHSP72. Physiological strain index (PSI) was attenuated in HOT (HST1 = 4.12 ± 0.58, HST2 = 3.60 ± 0.42; p = 0.007) as a result of a reduced HR (HST1 = 140 ± 14 b.min−1; HST2 131 ± 9 b.min−1 p = 0.0006) and Trectal (HST1 = 37.55 ± 0.18°C; HST2 37.45 ± 0.14°C; p = 0.018) during exercise. Whereas PSI did not change in HYP (HST1 = 4.82 ± 0.64, HST2 4.83 ± 0.63). Conclusion: Heat acclimation improved cellular and systemic physiological tolerance to steady state exercise in moderate hypoxia. Additionally we show, for the first time, that heat acclimation improved cycling time trial performance to a magnitude similar to that achieved by hypoxic acclimation.

Human monocyte heat shock protein 72 responses to acute hypoxic exercise after 3 days of exercise heat acclimation

The aim of this study was to determine whether short-term heat acclimation (STHA) could confer increased cellular tolerance to acute hypoxic exercise in humans as determined via monocyte HSP72 (mHSP72) expression. Sixteen males were separated into two matched groups. The STHA group completed 3 days of exercise heat acclimation; 60 minutes cycling at 50% V˙O2peak in 40°C 20% relative humidity (RH). The control group (CON) completed 3 days of exercise training in 20°C, 40% RH. Each group completed a hypoxic stress test (HST) one week before and 48 hours following the final day of CON or STHA. Percentage changes in HSP72 concentrations were similar between STHA and CON following HST1 (P = 0.97). STHA induced an increase in basal HSP72 (P = 0.03) with no change observed in CON (P = 0.218). Basal mHSP72 remained elevated before HST2 for the STHA group (P < 0.05) and was unchanged from HST1 in CON (P > 0.05). Percent change in mHSP72 was lower after HST2 in STHA compared to CON (P = 0.02). The mHSP72 response to hypoxic exercise was attenuated following 3 days of heat acclimation. This is indicative of improved tolerance and ability to cope with the hypoxic insult, potentially mediated in part by increased basal reserves of HSP72.

Effect of caffeine ingestion on torque and muscle activity during resistance exercise in men

Introduction: We examined the effect of caffeine ingestion on muscle torque production and muscle activity at different contraction speeds in trained men. Methods: 10 men (mean age ± SD = 22 ± 1.1 years) volunteered to participate. A double‐blind, randomized cross‐over design was used. Sixty minutes postingestion of caffeine (6 mg kg−1) or placebo, participants completed 6 repetitions of isokientic knee extension at 3 angular velocities (30°s−1, 150°s−1, 300°s−1) from which peak torque was determined. Electromyographic activity of the vastus medialis was also collected. Results: Repeated measures analysis of variance indicated that muscle torque production was significantly higher (P = 0.02) with caffeine compared with placebo. A significant (P = 0.02) substance by velocity interaction for muscle activity indicated significantly higher vastus medialis muscle activity in the presence of caffeine versus placebo, and this difference was amplified as angular velocity increased. Conclusions: Acute caffeine ingestion improves muscle performance and increases muscle activity during short‐duration maximal dynamic contractions. Muscle Nerve 50: 523–527, 2014

Human erythrocyte and plasma amino acid concentrations during exercise.

PURPOSE This investigation examined the effects of exercise and maltodextrin (Md) or placebo (Pl) ingestion on plasma and erythrocyte concentrations of amino acids. METHODS The erythrocyte and plasma concentrations of 17 amino acids, as well as plasma glucose and insulin, were analyzed in eight healthy trained male subjects before, during, and 25 min after 90-min cycle ergometer exercise at 65% peak oxygen uptake. The two treatments involved ingestion of orange-flavored water (Pl) or orange-flavored 10% maltodextrin solution (Md). RESULTS Two-way ANOVA revealed 1) that plasma concentrations of alanine and tyrosine changed significantly during the treatments, 2) that the plasma concentrations were significantly different between treatments for glycine and threonine, 3) that all erythrocyte concentrations increased significantly throughout the treatments except for arginine and tyrosine, and 4) that there were no significant differences in erythrocyte concentrations between the treatments. Three-way ANOVA highlighted the significant differences in the time responses between plasma and erythrocyte concentrations; the changes in erythrocyte levels from rest being significantly different from plasma for all amino acids except aspartic acid, glycine, and ornithine. Plasma glucose concentrations became elevated and remained above rest values in Md but fell below rest values in Pl: the differences in concentration between treatments were significant. Correspondingly, plasma insulin was significantly higher in Md during exercise. CONCLUSION These results highlight that far from being slow in the uptake of amino acids, the erythrocyte in fact sequesters amino acids at an appreciable rate during exercise without a corresponding elevation in the plasma amino acids. For a greater understanding of amino acid changes during exercise, the analysis of both plasma and erythrocytes is recommended.

Effect of Inspiration of 12%O2 (Balance N2) on Cardiac Output, Respiration, Oxygen Saturation, and Oxygen Delivery

Low arterial oxygen saturation (SaO(2)) will result in a reduced rate of arterial oxygen delivery to the tissues (DO(2)), unless there is a compensatory increase in cardiac output (CO) or haemoglobin concentration (Hb). An adequate DO(2) can therefore be maintained by increasing ventilation, CO, or both. Sustaining a tissue specific oxygen extraction is thought to play an important part in overall compensation. The present study has examined responses to acute hypoxic exposure in 8 volunteers (breathing 12% oxygen, balance nitrogen) and describes changes in CO, ventilation and the SaO(2). Aims included: examination of the extent of intersubject variations and seeing whether DO(2) was maintained. SaO(2), PCO(2), respiration (via stethograph) and Finapress (non-invasive) arterial blood pressure (BP) were recorded, firstly on air and then on 12% oxygen. CO was derived, off-line, from the BP record. CO was increased in 5 subjects (22%-45%) but was virtually unchanged in 3, and yet comparison for all 8 subjects showed that DO(2) on 12% oxygen was not significantly different from DO(2) on air (mean on air 1017 ml. min(-1); hypoxia 1080 ml. min(-1), p = 0.27). SaO(2) on 12% oxygen ranged between 85% and 93%. In conclusion, exposure to the same hypoxic gas mixture resulted in differing individual ventilatory and CO responses. However, DO(2) was well maintained.

Whole body precooling attenuates the extracellular HSP72, IL-6 and IL-10 responses after an acute bout of running in the heat

ABSTRACT The impact of whole-body precooling on the extracellular heat shock protein 72 (eHSP72) and cytokine responses to running in the heat is undefined. The aim of this study was to determine whether precooling would attenuate post-exercise eHSP72 and cytokine responses. Eight male recreational runners completed two 90-minute bouts of running at 65% O2max in 32 ± 0.9°C and 47 ± 6 % relative humidity (RH) preceded by either 60-minutes of precooling in 20.3 ± 0.3°C water (COOL) or 60 min rest in an air-conditioned laboratory (20.2 ± 1.7°C, 60 ± 3% RH; CON). eHSP72, TNF-α, IL-6, IL-10 IL-1ra were determined before and immediately after exercise. The elevation in post-exercise eHSP72 was attenuated after COOL (+0.04 ± 0.10 ng.mL−1) compared to CON (+ 0.29 ± 0.26 ng.mL−1;P < 0.001). No changes in TNF-α were observed at any stage. COOL reduced the absolute post-exercise change in IL-6 (P = 0.011) and IL-10 (P = 0.03) compared to CON. IL-1ra followed this trend (P = 0.063). A precooling-induced attenuation of eHSP72 and proinflammatory cytokines may aid recovery during multi-day sporting events, but could be counterproductive if a training response or adaptation to environmental stress is a desired outcome.

Relationships Between Measures of Physical Fitness Change When Age-Dependent Bias is Removed in a Group of Young Male Soccer Players

Abstract James, RS, Thake, CD, and Birch, SL. Relationships between measures of physical fitness change when age-dependent bias is removed in a group of young male soccer players. J Strength Cond Res 31(8): 2100–2109, 2017—Age-dependent bias is a key issue within talent identification of children, particularly when measures of physical fitness are used. Coaches in sport would benefit from a relatively straightforward method to remove age-dependent bias, enabling identification of children who are relatively high performers for their age. This study aimed to determine whether removal of age effects caused changes in the relationships between physical performance and anthropometric measures commonly used in talent identification and development systems. Sixty male soccer players, aged 11–17 years, underwent measures of anthropometry, muscular power, strength, sprint speed, and agility. Most absolute measures of performance were significantly correlated with each other, and all performance measures were significantly correlated with age. Age residuals were calculated, for all variables, to determine which players performed relatively well for their age and to investigate age-independent relationships between variables. In general, players with relatively fast sprint performance for their age were taller and had relatively high performance in jump power output and grip strength for their age (r > 0.25 and p < 0.025 in each case). Absolute sprint performance PC1 was significantly correlated with absolute agility performance PC1 (r = 0.473, p < 0.001). However, there was no significant relationship between age-independent measures of agility and any other measures. Usage of age residuals highlights performers that have relatively high physical fitness for their age. Such analyses may assist the talent identification and development processes as long as differential rates of physical development between players are also considered.

Next Day Subjective and Objective Recovery Indices Following Acute Low and High Training Loads in Academy Rugby Union Players

The aim of this study was to determine the sensitivity of selected subjective and objective monitoring assessments in detecting changes in group and individual responses to low and high load bouts of high intensity intermittent exercise. In a counterbalanced crossover design, Thirteen Academy Rugby Union players (mean ± SD: age: 18 ± 1 years) performed a low load (15 min) and a high load (90 min) bout of high intensity intermittent exercise (Loughborough Intermittent Shuttle Test) one week apart. Monitoring assessments were performed immediately prior to and 20 h following each trial. Subjective self-report Well-being Questionnaire (WQ) items showed small to large deteriorations following the high load compared to low load (d = 0.4–1.5, p = 0.03–0.57). A very large increase in resting HR (HRrest) (d = 2.1, p = 0.02), moderate decrease in heart rate variability (HRV) indices (d = 0.7, p = 0.04 and d = 0.7, p = 0.01 for the natural logarithm of the standard deviation of R-R intervals (ln SDNN) and the root square of the mean squared differences of successive R-R intervals (rMSSD), respectively) and no change in countermovement jump (d = 0.0, p = 0.97) were evident following the high load compared to low load. Individual WQ responses revealed 7/9, 7/9, 6/9, 6/9, 5/9, 3/9 and 1/9 participants reported deteriorations in recovery, sleep quality, motivation, muscle soreness, fatigue, stress and appetite, respectively, following the high load compared to low load. Individual analysis indicated a negative response following the high load compared to low load in HRrest, ln SDNN and ln rMSSD for 4/6, 2/6 and 1/6 participants, respectively. Selected WQ items detected group and individual responses to high load and low load highlighting their potential utility. However, objective assessments lacked the sensitivity to detect small individual changes.

Oscillations in Cardiac Output in Hypoxia with Periodic Breathing and Constant End-Tidal PCO2 at High Altitude (5,000 m)

At an altitude of 5,000 m during an ascent to Everest Base Camp in 1994 CBW experienced episodes of heavy breathing during a steady walk up a shallow gradient. Recorded respiration during similar exercise in the laboratory at base camp (DJC, 5,340 m) showed similar episodes of heavy breathing and yet end-tidal PCO2 remained steady. This led to the hypothesis that cardiac output (CO) oscillations, at the frequency of the hyper-ventilatory episodes, could be the cause of changing CO2 delivery to the lung. The ventilatory periodicity would then sustain the constant PCO2. The present study included measurement at rest and in mild exercise (35 W approx.) of changes in CO during a recent visit to the Hidden Valley in West Central Nepal at 5,000 m. PCO2, breathing, SaO2 and continuous arterial blood pressure (BP) were recorded. CO was derived from the BP record (PulseCOTM). Subject 04 showed vigorous periodic breathing with constant end-tidal PCO2 (PetCO2) but his BP record was technically unsatisfactory. However, there was a satisfactory BP record in subject 01 with strong periodicity in the respiratory and SaO2 records (period around 32 s). CO showed oscillations with amplitudes around 1.8 l per min (l min−1, range 1.5–2.8) with an average period of 32.1 s (range 28–42 s). The oscillations in CO partially compensated for SaO2 leading to near constant oxygen delivery (DO2). There was some PetCO2 oscillation. Subject 09 showed a run of seven more rapid CO oscillations during a resting record (period 25 s) resulting from respiratory gasps. The gasps preceded troughs in the CO record after a delay of approximately 21 s. PetCO2 was constant. Further subjects showed considerable variation in CO though not periodic. Data concerning haemoglobin, arterial oxygen saturation (SaO2) arterial oxygen content (CaO2) and calculated DO2 have also been provided for comparisons between air breathing, hypoxia at sea level and at altitude (both rest and mild exercise).