Assessment of Fatigue and Recovery in Sport: Narrative Review.

Fatigue is a phenomenon associated with decreases in both physical and cognitive performances and increases in injury occurrence. Competitive athletes are required to complete demanding training programs with high workloads to elicit the physiological and musculoskeletal adaptations plus skill acquisition necessary for performance. High workloads, especially sudden rapid increases in training loads, are associated with the occurrence of fatigue. At present, there is limited evidence elucidating the underlying mechanisms associating the fatigue generated by higher workloads and with an increase in injury risk. The multidimensional nature and manifestation of fatigue have led to differing definitions and dichotomies of the term. Consequently, a plethora of physiological, biochemical, psychological and performance markers have been proposed to measure fatigue and recovery. Those include self-reported scales, countermovement jump performance, heart rate variability, and saliva and serum biomarker analyses. The purpose of this review is to provide an overview of fatigue and recovery plus methods of assessments.

Effect of run training and cold-water immersion on subsequent cycle training quality in high-performance triathletes.

The purpose of the study was to investigate the effect of cold-water immersion (CWI) on physiological, psychological, and biochemical markers of recovery and subsequent cycling performance after intensive run training. Seven high-performance male triathletes (age: 28.6 ± 7.1 years; cycling VO2peak: 73.4 ± 10.2 ml · kg(-1) · min(-1)) completed 2 trials in a randomized crossover design consisting of 7 × 5-minute running intervals at 105% of individual anaerobic threshold followed by either CWI (10 ± 0.5° C) or thermoneutral water immersion (TNI; 34 ± 0.5° C). Subjects immersed their legs in water 5 times for 60 seconds with 60-second passive rest between each immersion. Nine hours after immersion, inflammatory and muscle damage markers, and perceived recovery measures were obtained before the subjects completed a 5-minute maximal cycling test followed by a high-quality cycling interval training set (6 × 5-minute intervals). Power output, heart rate, blood lactate (La), and rating of perceived exertion (RPE) were also recorded during the cycling time-trial and interval set. Performance was enhanced (change, ± 90% confidence limits) in the CWI condition during the cycling interval training set (power output [W · kg(-1)], 2.1 ± 1.7%, La [mmol · L(-1)], 18 ± 18.1%, La:RPE, 19.8 ± 17.5%). However, there was an unclear effect of CWI on 5-minute maximal cycling time-trial performance, and there was no significant influence on perceptual measures of fatigue/recovery, despite small to moderate effects. The effect of CWI on the biochemical markers was mostly unclear, however, there was a substantial effect for interleukin-10 (20 ± 13.4%). These results suggest that compared with TNI, CWI may be effective for enhancing cycling interval training performance after intensive interval-running training.

Measurement of steroid hormones in saliva: Effects of sample storage condition.

Measurement of steroid hormones in saliva is increasingly common in elite sport settings. However, this environment may enforce handling and storage practices that introduce error in measurement of hormone concentrations. We assessed the influence of storage temperature and duration on reproducibility of salivary steroid levels. Nine healthy adults provided morning and afternoon saliva samples on two separate occasions. Each sample was divided into identical saliva aliquots which were stored long-term (i.e. 28 and 84 days) at - 80°C or - 20°C (testing day 1), and short-term (i.e. 1, 3, 7 and 14 days) at 4°C or 20°C (testing day 2). Samples were analyzed for cortisol, testosterone and estradiol using ELISA. In non-freezer conditions, there was a decrease from baseline to 7 days in testosterone (- 26 ± 15%) and estradiol (- 58 ± 17%) but not cortisol concentrations (p < 0.001). This decrease was larger in samples stored at room temperature than in the refrigerator (p ≤ 0.01). There were small but significant changes in measured concentrations of all hormones after 28 and/or 84 days of storage in freezer conditions (p ≤ 0.01), but these were generally within 12% of baseline concentrations, and may be partly explained by inter-assay variability. Whole saliva samples to be analyzed for cortisol, testosterone and estradiol should be frozen at - 20°C or below within 24 h of collection, and analyzed within 28 days. Storage of samples for measurement of testosterone and estradiol at temperatures above - 20°C can introduce large error variance to measured concentrations.

Growth-hormone responses to consecutive exercise bouts with ingestion of carbohydrate plus protein.

Endocrine responses to repeated exercise have barely been investigated, and no data are available regarding the mediating influence of nutrition. On 3 occasions, participants ran for 90 min at 70% VO2max (R1) before a second exhaustive treadmill run at the same intensity (R2; 91.6 ± 17.9 min). During the intervening 4-hr recovery, participants ingested either 0.8 g sucrose · kg-1 · hr-1 with 0.3 g · kg-1 · hr-1 whey-protein isolate (CHO-PRO), 0.8 g sucrose · kg-1 · hr-1 (CHO), or 1.1 g sucrose · kg-1 · hr-1 (CHO-CHO). The latter 2 solutions therefore matched the former for carbohydrate or for available energy, respectively. Serum growth-hormone concentrations increased from 2 ± 1 µg/L to 17 ± 8 µg/L during R1 considered across all treatments (M ± SD; p ≤ .01). Concentrations were similar immediately after R2 irrespective of whether CHO or CHO-CHO was ingested (19 ± 4 µg/L and 19 ± 5 µg/L, respectively), whereas ingestion of CHO-PRO produced an augmented response (31 ± 4 µg/L; p ≤ .05). Growth-hormone-binding protein concentrations were unaffected by R1 but increased similarly across all treatments during R2 (from 414 ± 202 pmol/L to 577 ± 167 pmol/L; p ≤ .01), as was the case for plasma total testosterone (from 9.3 ± 3.3 nmol/L to 14.7 ± 4.6 nmol/L; p ≤ .01). There was an overall treatment effect for serum cortisol (p ≤ .05), with no specific differences at any given time point but lower concentrations immediately after R2 with CHO-PRO (608 ± 133 nmol/L) than with CHO (796 ± 278 nmol/L) or CHO-CHO (838 ± 134 nmol/L). Ingesting carbohydrate with added whey-protein isolate during short-term recovery from 90 min of treadmill running increases the growth-hormone response to a second exhaustive exercise bout of similar duration.

Dihydrotestosterone is elevated following sprint exercise in healthy young men.

Dihydrotestosterone (DHT) exerts both functional and signaling effects extending beyond the effects of testosterone in rodent skeletal muscle. As a primer for investigating the role of DHT in human skeletal muscle function, this study aimed to determine whether circulating DHT is acutely elevated in men following a bout of repeat sprint exercise and to establish the importance of training status and sprint performance to this response. Fourteen healthy active young men (Vo2max 61.0 ± 8.1 ml·kg body mass(-1)·min(-1)) performed a bout of repeat sprint cycle exercise at a target workload based on an incremental work-rate maximum (10 × 30 s at 150% Wmax with 90-s recovery). Venous blood samples were collected preexercise and 5 and 60 min after exercise. Five minutes after exercise, there were significant elevations in total testosterone (TT; P < 0.001), free testosterone (FT; P < 0.001), and DHT (P = 0.004), which returned to baseline after 1 h. Changes in DHT with exercise (5 min postexercise - preexercise) correlated significantly with changes in TT (r = 0.870; P < 0.001) and FT (r = 0.914; P < 0.001). Sprinting cadence correlated with changes in FT (r = 0.697; P = 0.006), DHT (r = 0.625; P = 0.017), and TT (r = 0.603; P = 0.022), and habitual training volume correlated with the change in TT (r = 0.569, P = 0.034). In conclusion, our data demonstrate that DHT is acutely elevated following sprint cycle exercise and that this response is influenced by cycling cadence. The importance of DHT in the context of exercise training and sports performance remains to be determined.

Growth Hormone Responses to Consecutive Exercise Bouts with Ingestion of Carbohydrate plus Protein.

Endocrine responses to repeated exercise have hardly been investigated and no data are available regarding the mediating influence of nutrition. On three occasions, participants ran for 90 min at 70% VO2max (R1) before a second exhaustive treadmill run at the same intensity (R2; 91.6 ± 17.9 min). During the intervening 4 h recovery, participants ingested either: (i) 0.8 g sucrose·kg-1·h-1 with 0.3 g·kg-1·h-1 whey protein isolate (CHO-PRO); (ii) 0.8 g sucrose·kg-1·h-1 (CHO) or; (iii) 1.1 g sucrose·kg-1·h-1 (CHO-CHO). The latter two solutions therefore matched the former for carbohydrate or for available energy, respectively. Serum growth hormone concentrations increased from 1.7±0.9 µg·l-1 to 16.7±7.8 µg·l-1 during R1 considered across all treatments (means±standard deviations; P≤0.01). Concentrations were similar immediately after R2 irrespective of whether CHO or CHO-CHO was ingested (19±4 µg·l-1 and 19±5µg·l-1, respectively), whereas ingestion of CHO-PRO produced an augmented response (31±4µg·l-1; P≤0.05). Growth hormone binding protein concentrations were unaffected by R1 but increased similarly across all treatments during R2 (414±202 pmol·l-1 to 577±167 pmol·l-1; P≤0.01), as was the case for plasma total testosterone (9.3±3.3 nmol·l-1 to 14.7±4.6 nmol·l-1; P≤0.01). There was an overall treatment effect for serum cortisol (P≤0.05), with no specific differences at any given time-point but lower concentrations immediately after R2 with CHO-PRO (608±133 nmol·l-1) than CHO (796±278 nmol·l-1) or CHO-CHO (838±134 nmol·l-1). Ingesting carbohydrate with added whey protein isolate during short-term recovery from 90 minutes of treadmill running increases the growth hormone response to a second exhaustive exercise bout of similar duration.

Isocaloric carbohydrate versus carbohydrate-protein ingestion and cycling time-trial performance.

This study was designed to compare the effects of energy-matched carbohydrate (CHO) and carbohydrate-protein (CHO-PRO) supplements on cycling time-trial performance. Twelve competitive male cyclists and triathletes each completed 2 trials in a randomized and counterbalanced order that were separated by 5-10 d and applied in a double-blind manner. Participants performed a 45-min variable-intensity exercise protocol on a cycle ergometer while ingesting either a 9% CHO solution or a mixture of 6.8% CHO plus 2.2% protein in volumes providing 22 kJ/kg body mass. Participants were then asked to cycle 6 km in the shortest time possible. Blood glucose and lactate concentrations were measured every 15 min during exercise, along with measures of substrate oxidation via indirect calorimetry, heart rate, and ratings of perceived exertion. Mean time to complete the 6-km time trial was 433 + or - 21 s in CHO trials and 438 + or - 22 s in CHO-PRO trials, which represents a 0.94% (CI: 0.01, 1.86) decrement in performance with the inclusion of protein (p = .048). However, no other variable measured in this study was significantly different between trials. Reducing the quantity of CHO included in a supplement and replacing it with protein may not represent an effective nutritional strategy when the supplement is ingested during exercise. This may reflect the central ergogenic influence of exogenous CHO during such activity.

Systemic indices of skeletal muscle damage and recovery of muscle function after exercise: effect of combined carbohydrate-protein ingestion.

Previous studies indicate that exercise-induced muscle damage may be attenuated when protein is included in a carbohydrate recovery supplement. This study was designed to examine systemic indices of muscle damage, inflammation, and recovery of muscle function, following strenuous exercise, with ingestion of either carbohydrate alone or a carbohydrate-protein mixture. Seventeen highly trained volunteers participated in 2 trials in a randomized order, separated by approximately 9 weeks. Each trial involved 90 min of intermittent shuttle-running, either with ingestion of a 9% sucrose solution during and for 4 h after (1.2 g.kg-1 body mass.h-1) or with the same solution plus 3% whey protein isolate (0.4 g.kg-1 body mass.h-1). Blood was sampled throughout and 24 h after each trial to determinate the systemic indices of muscle damage and inflammation. An isokinetic dynamometer was used to establish reliable baseline measurements of peak isometric torque for knee and hip flexors and extensors, which were then followed-up at 4-, 24-, 48-, and 168-h postexercise. The exercise protocol resulted in significantly elevated variables indicative of muscle damage and inflammation, while peak isometric torque was immediately reduced by 10%-20% relative to baseline, across all muscle groups tested. However, none of these responses varied in magnitude or time-course between the treatments, or between participants' first and second trials. The addition of whey protein isolate to a dietary carbohydrate supplement ingested during and for 4 h following strenuous exercise did not attenuate systemic indices of muscle damage or inflammation, nor did it restore muscle function more rapidly than when the carbohydrate fraction was ingested alone.