Edith M. Peters

Influence of vitamin C supplementation on cytokine changes following an ultramarathon.

The influence of vitamin C supplementation on the pattern of change in plasma cytokine concentrations was measured in 29 runners following a 90-km ultramarathon. The study was based on a 3 (groups) by 4 (blood samples at 16 prerace, postrace, and 24 h and 48 h postrace) repeated measures design. Groups included placebo control (n = 7) and two groups supplementing vitamin C at 500 mg/day (vit C-500, n = 10) or 1500 mg/day (vit C-1500, n = 12) for 7 days before the race, on race day, and for 2 days after the race. All measured plasma cytokine concentrations were significantly elevated immediately postrace, with the magnitude of increase for tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) much smaller than for IL-6, IL-10, IL-8, and IL-1 receptor antagonist (IL-1RA). Cortisol increased in all groups immediately after the race but significantly less in the vit C-1500 group. Group x time interaction statistics were not significant for any of the plasma cytokines. However, when the placebo and vit C-500 groups were combined (n = 17) and compared with the vit C-1500 group (n = 12), immediate postrace plasma concentrations were significantly lower in the vit C-1500 group for IL-1RA (-57%) and IL-10 (-57%), with a trend measured for IL-6 (-27%, p = 0.11) and IL-8 (-26%, p = 0.14). In summary, runners completing the 90-km Comrades Ultramarathon experienced strong increases in concentrations of plasma IL-6, IL-10, IL-1RA, and IL-8. These increases were attenuated in runners ingesting 1500 mg but not 500 mg vitamin C supplements for 1 week prior to the race and on race day.

Upper respiratory tract infection symptoms in ultramarathon runners not related to immunoglobulin status.

Objective:To determine the association between variation in exercise load, immunoglobulin (Ig) status, and self-reported symptoms of upper respiratory tract infection (URTI) in ultramarathon runners. Design:Longitudinal observational field study. Setting:Four weeks before and 2 weeks after an 86.5-km Comrades Marathon, South Africa. Participants:Fourteen randomly selected, amateur, male, ultramarathon runners. Main Outcome Measures:Daily record of training and URTI symptom incidence. Salivary IgA and IgM at 28 days, 14 days, and 1 day (01PRE) before the race, immediately post race (IPR) and 1 (01 PR), 3, and 14 days post race. Serum cortisol, IgG, IgM, and IgA concentrations at 01PRE, IPR, and 01PR. Results:Mean weekly training distance varied from 89.4 kilometers per week (28.9 kilometers per week) to 4.2 kilometers per week (6.7 kilometers per week). Absolute and relative mucosal IgA and IgM concentrations were unaffected by pre-race taper in training volume (P > 0.05). IgA and IgM secretion rates decreased post race (P = 0.018; 0.008), returning to baseline by 01PR. Blood leukocyte, serum cortisol, and serum IgG concentrations increased at IPR (P < 0.001, <0001) and 01PR (P = 0.009), respectively. Upper respiratory tract infection symptom incidence was highest at 28PRE and 7 to 14 days post race but not related to salivary IgA and IgM secretion rates. Eight subjects (57%) who reported URTI symptoms pre race also reported these during days 7 to 14 post race. Conclusions:Upper respiratory tract infection symptom incidence was not associated with secretory Ig concentrations. Reactivation of pre-race viruses during the 2 weeks post race and exercise-induced inflammatory response are proposed as causes of the elevated URTI incidence at 28PRE and 7 to 14 days post race.

Intestinal temperature, heart rate, and hydration status in multiday trail runners.

Objective:To assess heart rate (HR), intestinal body temperature (Tintest), and hydration status changes and relationships in 12 participants in a 3-day trail run. Design:Descriptive field study. Setting:Three Cranes Challenge trail run, in Karkloof, KwaZulu-Natal, South Africa. Participants:Twelve (5 men and 7 women) amateur runners. Interventions:Trail run of 95 km divided into 3 stages: elevation gains on the 3 days, 1020, 1226, and 680 m, respectively. Main Outcome Measures:Changes in HR, Tintest, serum osmolality, and body mass. Results:Environmental conditions were consistently mild (ambient temperature range, 11.5-22.8°C; maximum relative humidity range, 95%-97%), average running speed varied from 9.00 to 5.14 minutes/km, and distance covered in the 3 stages ranged from 32 (stages 1 and 3) to 40 km (stage 2). Mean HR ranged from 134 to 171 beats per minute in the 12 athletes during the trail events and averaged at 150 beats per minute, whereas Tintest ranged between 36.1 and 40.2°C. The correlation between maximum Tintest and percent age-predicted maximum HR (n = 12) was significant (R = 0.58; P < 0.05), whereas the correlation between maximum Tintest and serum osmolality or body mass did not reach significance (R = 0.16, 0.13; P > 0.05). Conclusions:This study provides evidence in support of the contention that maximum Tintest is more closely related to metabolic rate during trail running than percent dehydration. The findings do not support an increase in core body temperature with a change in serum osmolality or body mass.

Markers of hydration status in a 3-day trail running event

Objective:To examine the relationships between changes in static prestage and poststage measures of commonly used hematological and urinary markers of hydration status and body mass (BM) in participants in a 3-day trail run. Design:Descriptive field study. Setting:Three Cranes Challenge trail run, South Africa. Participants:Twenty (6 men and 14 women) amateur runners. Interventions:In stage 1 (S1), 29.3 km and 37.9 km in stage 2 (S2), and 27.8 km in stage 3 (S3). Main Outcome Measures:Prestage and poststage individual changes in serum osmolality (Sosm), serum sodium (s[Na+]), plasma volume (PV), urine osmolality (Uosm), urine specific gravity (Usg), and BM. Results:Consistently, mild environmental conditions were experienced on the 3 days of the race (ambient temperature range, 11.5-22.8°C). Mean Sosm increased by 5 ± 6, 7 ± 9, and 3 ± 4 mOsm/kg during S1, S2, and S3, respectively, and returned to baseline pre-S2 and pre-S3. The correlation between individual prestage and poststage changes in Sosm, Uosm, and Usg (n = 60) were nonsignificant (P > 0.05; r = 0.0047, r = 0.0074). There was a significant, but relatively low correlation between changes in Sosm and percentage reduction in BM (r = 0.35; P < 0.01) and prechange and postchange in s[Na+] (r = 0.45; P < 0.001). Conclusions:Serum osmality values confirm appropriate interstage rehydration. Changes in Uosm, Usg, BM, s[Na+], and PV are not closely related to changes in Sosm as markers of hydration assessment in multiday events in which single static measures of hydration status are required. These measures of hydration station status are therefore not recommended in this field setting.

Phadiatop testing in assessing predisposition to respiratory tract symptoms of allergic origin in athletes

OBJECTIVES To validate the use of the Phadiatop test as a predictor of allergy-associated respiratory tract symptoms (RTS) in trail runners. METHODS The incidence of self-reported RTS was documented in 16 runners for 31 days and related to the Phadiatop status and circulating markers of allergic responses (changes in concentrations of serum IgE (sIgE), differential leucocyte counts) at 8 time points before, during and after a 3-day 95 km trail run. RESULTS Twelve (75%) athletes, of whom 7 (58%) were Phadiatoppositive, presented with post-race RTS. A peak sIgE concentration >100 IU/ml accompanied RTS in only 4 (57%) of the symptomatic Phadiatop-positive subjects. There was no significant difference between the eosinophil and basophil concentrations of the positive and negative groups (p>0.05). One Phadiatop-negative subject presented with RTS as well as a peak sIgE concentration >100 IU/ml. CONCLUSION The Phadiatop assay does not accurately predict the development of post-exercise RTS of allergic origin in trail runners.