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AB Purpose: Previous work identified an asymmetry in tissue desaturation changes in the left and right quadriceps muscles during on-ice skating at maximal speed in males. The effect of changing race distance on the magnitude of desaturation or leg asymmetry is unknown. Methods: Six elite male skaters (age = 23 +/- 1.8 yr, height = 1.8 +/- 0.1 m, mass = 80.1 +/- 5.7 kg, midthigh skinfold thickness = 7 +/- 2 mm) and four elite female skaters (age = 21 +/- 4 yr, height = 1.6 +/- 0.1 m, mass = 65.2 +/- 4.3 kg, midthigh skinfold thickness = 10 +/- 1 mm) were studied. Subjects completed time trials over three race distances. Blood lactate concentration and O2 uptake measurements were combined with near-infrared spectroscopy measures of muscle oxygenation (TSI) and blood volume (tHb) in the right and left vastus lateralis. Results: Neither race distance nor gender had a significant effect on the magnitude of maximal muscle desaturation ([DELTA]TSImax). Pattern of local changes in tHb during individual laps was dependent upon subtle differences in skating technique used for the different race distances. Linear regression analysis revealed asymmetry between the right and left leg desaturation in males during the final stages of each race distance, but not in females. At all race distances, local muscle desaturation reached maximal values much more quickly than global V[spacing dot above]O2peak. Conclusion: The use of wearable near-infrared spectroscopy devices enabled measurement of muscle oxygenation during competitive race simulation, thus providing unique insight into the effects of velocity and technique changes on local muscle oxygenation. This may have implications for training and race pacing in speed skating

The aim of the study was to determine the influence of immediate and 1-hr-delayed carbohydrate (CHO) and protein (PRO) feeding after prolonged exercise on leukocyte trafficking, bacterially stimulated neutrophil degranulation, saliva secretory IgA (S-IgA) responses, and circulating stress hormones. In randomized order, separated by 1 wk, 9 male runners completed 3 feeding interventions after 2 hr of running at 75% VO2max. During control (CON), participants received water (12 ml/kg body mass [BM]) immediately and 1 hr postexercise. During immediate feeding (IF), participants received a CHO-PRO solution equal to 1.2 g CHO/kg BM and 0.4 g PRO/kg BM immediately postexercise and water 1 hr postexercise. During delayed feeding (DF), participants received water immediately postexercise and CHO-PRO solution 1 hr postexercise. Unstimulated saliva and venous blood samples were collected preexercise, immediately postexercise, and every 20 min until 140 min postexercise. No significant interactions were observed for circulating leukocytes and T-lymphocyte subset counts, S-IgA secretion rate, or plasma cortisol, epinephrine, or norepinephrine concentration. Bacterially stimulated neutrophil degranulation decreased during recovery on CON and DF (24% and 31%, respectively, at 140 min; p < .01) but not on IF. Compared with CON, neutrophil degranulation was higher on IF at 100 min postexercise and higher on IF than DF at 80 min and 100 min onward postexercise (p < .05). Ingestion of a CHO-PRO solution immediately after, but not 1 hr after, prolonged strenuous exercise prevented the decrease in neutrophil degranulation but did not alter circulating stress hormone, leukocyte trafficking, or S-IgA responses. Further research should identify the independent effect of different quantities of CHO and PRO ingestion during recovery on neutrophil responses and other aspects of immune function.

A one night period without sleep is not uncommon amongst athletes travelling across time zones and military personnel during training and operations. However, the effect of one night without sleep on immune indices in response to strenuous exercise remains unknown. The objective was to determine the effect of one night without sleep on immune indices in response to subsequent strenuous exercise. Using a repeated measures cross-over design, on one occasion eleven male participants slept normally (CON) and on another they were sleep deprived for 30 h (SDEP). After 30 h participants performed 30 min steady state (SS) treadmill exercise at 60% VO2max followed by a 30 min treadmill time trial (TT). Blood and saliva samples were collected at 0 h, 30 h, post-SS, post-TT, 2 h post-TT and 18 h post-TT. Circulating leukocyte and T-lymphocyte subset counts, bacterially-stimulated neutrophil degranulation, saliva secretory immunoglobulin A (S-IgA) and plasma cortisol were determined. No trial x time interactions were observed for immune indices and plasma cortisol. A leukocytosis, neutrophilia, and lymphocytosis was observed post-TT compared with 30 h (P < 0.01). Also, at post-TT compared with 30 h an increase in circulating T-lymphocyte CD3 + (55%) and CD8 + (67%) counts (P < 0.05), a decrease in neutrophil degranulation (20%; P < 0.05) and an increase in S-IgA concentration (83%) was observed (P < 0.01). Plasma cortisol concentration increased post-TT (62%) compared with post-SS (P < 0.01). In conclusion, a 30 h period of sleep deprivation does not alter leukocyte trafficking, neutrophil degranulation or S-IgA responses either at rest or after submaximal and strenuous exercise.

The aim of this study was to determine the effects of prolonged exercise in hot conditions on saliva IgA (s-IgA) responses in trained cyclists. On two occasions, in random order and separated by 1 week, 12 male cyclists cycled for 2 h on a stationary ergometer at 62 (3)% VO2 max [194 (4) W; mean (SEM)], on one occasion (HOT: 30.3°C, 76% RH) and on another occasion (CONTROL: 20.4°C, 60% RH). Water was available ad-libitum. Venous blood samples and 2-min whole unstimulated saliva samples were collected at pre, post and 2 h post-exercise. The s-IgA concentration was determined using a sandwich-type ELISA. Exercising heart rate, rating of perceived exertion, rectal temperature, corrected body mass loss (P

Firstly, to identify whether saliva flow rate, osmolality, and total protein are potential markers of hydration, we compared changes in these parameters with changes in plasma osmolality during progressive dehydration. Secondly, we compared the sensitivity of saliva parameters to track hydration changes with the sensitivity of urine osmolality. Thirdly, to test the hypothesis that dehydration, rather than neuroendocrine regulation, is responsible for the decrease in saliva flow rate during prolonged exercise, we compared flow rate and catecholamine responses to prolonged exercise with and without fluids.colon; Fifteen males (plasma osmolality 289 +/- 4 mOsmol x kg(-1); mean +/- SD) exercised (30 degrees C, 70% RH) with no fluid intake (NFI) until body mass loss (BML) of 1.1, 2.1, and 3.0% and on another occasion with fluid intake (FI) to offset losses.colon; Plasma and urine osmolality increased during NFI (plasma osmolality 3.0% BML: 298 +/- 4 mOsmol x kg(-1); P0.01). Saliva flow rate decreased (P0.01), saliva total protein increased (P0.01), and saliva osmolality increased from preexercise (50 +/- 11 mOsmol x kg(-1)) to 3.0% BML (105 +/- 41 mOsmol x kg(-1)) during NFI (P0.01). Saliva osmolality, urine osmolality, and saliva total protein correlated strongly with plasma osmolality during dehydration (r 0.87, 0.83, and 0.91, respectively; P0.01). During the FI trial, saliva flow rate and osmolality remained unchanged. Plasma catecholamine concentration increased during exercise (P0.01) with no difference between trials.colon; Saliva osmolality and total protein appear to be as sensitive as urine osmolality to track hydration changes during hypertonic-hypovolemia. These results also suggest that dehydration has a greater involvement in the decrease in saliva flow rate during prolonged exercise than neuroendocrine regulation.

Portable near-infrared spectroscopy (NIRS) has been shown to be a useful and reliable tool for monitoring muscle oxygenation and blood volume changes during dynamic exercise in elite athletes. The wearable nature of such technology permits the measurement of specific muscles/muscle groups during realistic sport-specific exercise tasks in an outdoor environment. The aim of this case study was to observe the effect on arm and leg muscle oxygenation of roller skiing over a typical outdoor racing course. Such information is required by coaches in order to ascertain whether an athlete is using the correct technique at different stages of the course. Two wearable NIRS devices (PortaMon, Artinis Medical Systems) were used to compare muscle tissue oxygen saturation (TSI%) and total haemoglobin (tHb) changes in the quadriceps muscle group (vastus lateralis) and a muscle of the upper arm (triceps) during roller skiing. During the flat section, quadriceps ΔTSI remained steady in both subjects, whereas triceps ΔTSI showed a reduction (−10 %). During the steep uphill section of the course, arm and leg TSI decreased equally in one subject (ΔTSI = −10 %), whereas there was a difference between the two muscle groups in the other subject (ΔTSIquadriceps = −2 %; ΔTSItriceps = −7 %). A difference was also seen between subjects during the downhill section of the course. This study presents the first example of the use of portable NIRS to assess oxygenation and blood volume changes in multiple muscle groups during roller skiing in a realistic, outdoor setting.

PURPOSE: It has been suggested that, because of the low sitting position in short-track speed skating, muscle blood flow is restricted, leading to decreases in tissue oxygenation. Therefore, wearable wireless-enabled near-infrared spectroscopy (NIRS) technology was used to monitor changes in quadriceps muscle blood volume and oxygenation during a 500-m race simulation in short-track speed skaters. METHODS: Six elite skaters, all of Olympic standard (age = 23 ± 1.8 yr, height = 1.8 ± 0.1 m, mass = 80.1 ± 5.7 kg, midthigh skinfold thickness = 7 ± 2 mm), were studied. Subjects completed a 500-m race simulation time trial (TT). Whole-body oxygen consumption was simultaneously measured with muscle oxygenation in right and left vastus lateralis as measured by NIRS. RESULTS: Mean time for race completion was 44.8 ± 0.4 s. VO 2 peaked 20 s into the race. In contrast, muscle tissue oxygen saturation (TSI%) decreased and plateaued after 8 s. Linear regression analysis showed that right leg TSI% remained constant throughout the rest of the TT (slope value = 0.01), whereas left leg TSI% increased steadily (slope value = 0.16), leading to a significant asymmetry (P < 0.05) in the final lap. Total muscle blood volume decreased equally in both legs at the start of the simulation. However, during subsequent laps, there was a strong asymmetry during cornering; when skaters traveled solely on the right leg, there was a decrease in its muscle blood volume, whereas an increase was seen in the left leg. CONCLUSIONS: NIRS was shown to be a viable tool for wireless monitoring of muscle oxygenation. The asymmetry in muscle desaturation observed on the two legs in short-track speed skating has implications for training and performance. © 2012 by the American College of Sports Medicine.

The aim was to investigate the effects of 48 hr of fluid, energy, or combined fluid and energy restriction on circulating leukocyte and lymphocyte subset counts (CD3+, CD4+, and CD8+) and bacterially stimulated neutrophil degranulation at rest and after exercise. Thirteen healthy men (M ± SEM age 21 ± 1 yr) participated in 4 randomized 48-hr trials. During control (CON) participants received their estimated energy (2,903 ± 17 kcal/day) and fluid (3,912 ± 140 ml/day) requirements. During fluid restriction (FR) they received their energy requirements and 193 ± 19 ml/day water to drink. During energy restriction (ER) they received their fluid requirements and 290 ± 6 kcal/day. Fluid and energy restriction (F+ER) was a combination of FR and ER. After 48 hr, participants performed a 30-min treadmill time trial (TT) followed by rehydration (0–2 hr) and refeeding (2–6 hr). Circulating leukocyte and lymphocyte counts remained unchanged for CON and FR. Circulating leukocyte, lymphocyte, CD3+, and CD4+ counts decreased by ~20% in ER and ~30% in F+ER by 48 hr (p < .01), returning to within 0-hr values by 6 hr post-TT. Circulating neutrophil count and degranulation were unaltered by dietary restriction at rest and after TT. In conclusion, a 48-hr period of ER and F+ER, but not FR, decreased circulating leukocyte, lymphocyte, CD3+, and CD4+ counts but not neutrophil count or degranulation. Circulating leukocyte and lymphocyte counts normalized on refeeding. Finally, dietary restriction did not alter circulating leukocyte, lymphocyte, and neutrophil responses to 30 min of maximal exercise.

To determine the effect of a 48-h period of either fluid restriction (FR), energy restriction (ER), or fluid and energy restriction (F + ER) on 30-min treadmill time trial (TT) performance in temperate conditions.Thirteen males participated in four randomized 48-h trials (mean +/- SD: age, 21 +/- 3 yr; VO2max 50.9 +/- 4.3 mL x kg(-1) x min(-1)). Control (CON) participants received their estimated energy (2903 +/- 199 kcal x d(-1)) and water (3912 +/- 500 mL x d(-1)) requirements. For FR, participants received their energy requirements and 193 +/- 50 mL x d(-1) water to drink, and for ER, participants received their water requirements and 290 +/- 20 kcal x d(-1). F + ER was a combination of FR and ER. After 48 h, participants performed a 30-min treadmill TT in temperate conditions (19.7 +/- 0.6 degrees C). A separate investigation (N = 10) showed the TT to be highly reproducible (CV 1.6%).Body mass loss (BML) was 0.6 +/- 0.4% (CON), 3.2 +/- 0.5% (FR), 3.4 +/- 0.3% (ER), and 3.6 +/- 0.3% (F + ER). Compared with CON (6295 +/- 513 m), less distance was completed on ER (10.3%) and F + ER (15.0%: P0.01). Although less distance was completed on FR (2.8%), this was not significantly different from CON.These results show a detrimental effect of a 48-h period of ER but no significant effect of FR on 30-min treadmill TT performance in temperate conditions. Therefore, these results do not support the popular contention that modest hypohydration (2-3% BML) significantly impairs endurance performance in temperate conditions.

The effects of the first 19 weeks of U.K. Parachute Regiment (PARA) training on upper respiratory tract infection (URTI) incidence and immune function (circulating leukocyte counts, lymphocyte subsets, lipopolysaccharide-stimulated neutrophil degranulation, and salivary immunoglobulin A concentrations) were investigated for 14 PARA recruits and 12 control subjects. No significant differences were reported between groups for the number or duration of URTIs, lymphocyte subsets, or salivary immunoglobulin A concentrations during training. URTI incidence was greater in the PARA group at weeks 2 and 3 (p < 0.05), coinciding with a decrease in circulating leukocyte and lymphocyte counts (p < 0.05). Neutrophil degranulation was similar in the PARA and control groups at weeks 0 and 19. Decreases in saliva flow rate occurred in the PARA group at week 15 and weeks 18 to 20 (p < 0.05). These results show a limited effect of PARA training on URTI incidence and immune function. The progressive decrease in saliva flow rate during PARA training may indicate an ensuing state of hypohydration.