The effects of ionized and nonionized compression garments on sprint and endurance cycling

ABSTRACT: Burden, RJ and Glaister, M. The effects of ionized and nonionized compression garments on sprint and endurance cycling. J Strength Cond Res 26(10): 2837-2843, 2012-The aim of this study was to examine the effects of ionized and nonionized compression tights on sprint and endurance cycling performance. Using a randomized, blind, crossover design, 10 well-trained male athletes (age: 34.6 ± 6.8 years, height: 1.80 ± 0.05 m, body mass: 82.2 ± 10.4 kg, V[Combining Dot Above]O2max: 50.86 ± 6.81 ml·kg·min) performed 3 sprint trials (30-second sprint at 150% of the power output required to elicit V[Combining Dot Above]O2max [pV[Combining Dot Above]O2max] + 3 minutes recovery at 40% pV[Combining Dot Above]O2max + 30-second Wingate test + 3 minutes recovery at 40% pV[Combining Dot Above]O2max) and 3 endurance trials (30 minutes at 60% pV[Combining Dot Above]O2max + 5 minutes stationary recovery + 10-km time trial) wearing nonionized compression tights, ionized compression tights, or standard running tights (control). There was no significant effect of garment type on key Wingate measures of peak power (grand mean: 1,164 ± 219 W, p = 0.812), mean power (grand mean: 716 ± 68 W, p = 0.800), or fatigue (grand mean: 66.5 ± 6.9%, p = 0.106). There was an effect of garment type on blood lactate in the sprint and the endurance trials (p < 0.05), although post hoc tests only detected a significant difference between the control and the nonionized conditions in the endurance trial (mean difference: 0.55 mmol·L, 95% likely range: 0.1-1.1 mmol·L). Relative to control, oxygen uptake (p = 0.703), heart rate (p = 0.774), and time trial performance (grand mean: 14.77 ± 0.74 minutes, p = 0.790) were unaffected by either type of compression garment during endurance cycling. Despite widespread use in sport, neither ionized nor nonionized compression tights had any significant effect on sprint or endurance cycling performance.     

The effect of graduated compression stockings on running performance

The aim of this study was to examine the effects of wearing different grades of graduated compression stockings (GCS) on 10-km running performance. After an initial familiarization run, 9 male and 3 female competitive runners (VO?max 68.7 ± 5.8 ml·kg?1·min?1) completed 4 10-km time trials on an outdoor 400-m track wearing either control (0 mm Hg; Con), low (12-15 mm Hg; Low), medium (18-21 mm Hg; Med), or high (23-32 mm Hg; Hi) GCS in a randomized counterbalanced order. Leg power was assessed pre and postrun via countermovement jump using a jump mat. Blood-lactate concentration was assessed pre and postrun, whereas heart rate was monitored continuously during exercise. Perceptual scales were used to assess the comfort, tightness, and any pain associated with wearing GCS. There were no significant differences in performance time between trials (p = 0.99). The change in pre to postexercise jump performance was lower in Low and Med than in Con (p < 0.05). Mean heart rate (p = 0.99) and blood lactate (p = 1.00) were not different between trials. Participants rated Con and Low as more comfortable than Med and Hi (p < 0.01), Med and Hi were rated as tighter than Low (p < 0.01), all GCS were rated as tighter than Con (p < 0.01), and Hi was associated with the most pain (p < 0.01). In conclusion, GCS worn by competitive runners during 10-km time trials did not affect performance time; however Low and Med GCS resulted in greater maintenance of leg power after endurance exercise. Athletes rated low-grade GCS as most comfortable garments to wear during exercise.     

Postexercise carbohydrate-protein supplementation improves subsequent exercise performance and intracellular signaling for protein synthesis

Postexercise carbohydrate-protein (CHO + PRO) supplementation has been proposed to improve recovery and subsequent endurance performance compared to CHO supplementation. This study compared the effects of a CHO + PRO supplement in the form of chocolate milk (CM), isocaloric CHO, and placebo (PLA) on recovery and subsequent exercise performance. Ten cyclists performed 3 trials, cycling 1.5 hours at 70% VO?max plus 10 minutes of intervals. They ingested supplements immediately postexercise and 2 hours into a 4-hour recovery. Biopsies were performed at recovery minutes 0, 45, and 240 (R0, R45, REnd). Postrecovery, subjects performed a 40-km time trial (TT). The TT time was faster in CM than in CHO and in PLA (79.43 ± 2.11 vs. 85.74 ± 3.44 and 86.92 ± 3.28 minutes, p ≤ 0.05). Muscle glycogen resynthesis was higher in CM and in CHO than in PLA (23.58 and 30.58 vs. 7.05 μmol·g?1 wet weight, p ≤ 0.05). The mammalian target of rapamycin phosphorylation was greater at R45 in CM than in CHO or in PLA (174.4 ± 36.3 vs. 131.3 ± 28.1 and 73.7 ± 7.8% standard, p ≤ 0.05) and at REnd in CM than in PLA (94.5 ± 9.9 vs. 69.1 ± 3.8%, p ≤ 0.05). rpS6 phosphorylation was greater in CM than in PLA at R45 (41.0 ± 8.3 vs. 15.3 ± 2.9%, p ≤ 0.05) and REnd (16.8 ± 2.8 vs. 8.4 ± 1.9%, p ≤ 0.05). FOXO3A phosphorylation was greater at R45 in CM and in CHO than in PLA (84.7 ± 6.7 and 85.4 ± 4.7 vs. 69.2 ± 5.5%, p ≤ 0.05). These results indicate that postexercise CM supplementation can improve subsequent exercise performance and provide a greater intracellular signaling stimulus for PRO synthesis compared to CHO and placebo.     

Effects of gradual-elastic compression stockings on running economy, kinematics, and performance in runners

We investigated the effect of gradual-elastic compression stockings (GCSs) on running economy (RE), kinematics, and performance in endurance runners. Sixteen endurance trained athletes (age: 34.73 ± 6.27 years; VO2max: 62.83 ± 9.03 ml·kg(-1)·min(-1); 38 minutes in 10 km; 1 hour 24 minutes in half marathon) performed in random order 4 bouts of 6 minutes at a recent half-marathon pace on a treadmill to evaluate RE with or without GCSs. Subsequently, 12 athletes were divided into 2 equal groups matched by their VO2max, and they performed a time limit test (T(lim)) on a treadmill at 105% of a recent 10-km pace with or without GCSs for evaluation of physiological responses and running kinematics. There were no significant differences in the RE test in all of the variables analyzed for the conditions, but a moderate reproducibility for some physiological responses was detected in the condition with GCSs. In the T(lim), the group that wore GCSs reached a lower % of maximum heart rate (HRmax) compared with the control group (96.00 ± 2.94 vs. 99.83 ± 0.40) (p = 0.01). Kinematics did not differ between conditions during the T(lim) (p > 0.05). There were improvement trends for time to fatigue (337 vs. 387 seconds; d = 0.32) and a lower VO2peak (≈53 vs. 62 ml·kg(-1)·min(-1); d = 1.19) that were detected with GCSs during the T(lim). These results indicate that GCSs reduce the % of HRmax reached during a test at competition pace. The lower reproducibility of the condition with GCSs perhaps suggests that athletes may possibly need an accommodation period for systematically experiencing the benefits of this garment, but this hypothesis should be further investigated.     

Do compression garments enhance the active recovery process after high-intensity running?

Lovell, DI, Mason, DG, Delphinus, EM, and McLellan, CP. Do compression garments enhance the active recovery process after high-intensity running? J Strength Cond Res 25(12): 3264-3268, 2011-This study examined the effect of wearing waist-to-ankle compression garments (CGs) on active recovery after moderate- and high-intensity submaximal treadmill running. Twenty-five male semiprofessional rugby league players performed two 30-minute treadmill runs comprising of six 5-minute stages at 6 km·h, 10 km·h, approximately 85% VO(2)max, 6 km·h as a recovery stage followed by approximately 85% VO(2)max and 6 km·h wearing either CGs or regular running shorts in a randomized counterbalanced order with each person acting as his own control. All stages were followed by 30 seconds of rest during which a blood sample was collected to determine blood pH and blood lactate concentration [La]. Expired gases and heart rate (HR) were measured during the submaximal treadmill tests to determine metabolic variables with the average of the last 2 minutes used for data analysis. The HR and [La] were lower (p ≤ 0.05) after the first and second 6 km·h recovery bouts when wearing CGs compared with when wearing running shorts. The respiratory exchange ratio (RER) was higher and [La] lower (p ≤ 0.05) after the 10 km·h stage, and only RER was higher after both 85% VO(2)max stages when wearing CGs compared with when wearing running shorts. There was no difference in blood pH at any exercise stage when wearing the CGs and running shorts. The results of this study indicate that the wearing of CGs may augment the active recovery process in reducing [La] and HR after high-intensity exercise but not effect blood pH. The ability to reduce [La] and HR has important consequences for many sports that are intermittent in nature and consist of repeated bouts of high-intensity exercise interspersed with periods of low-intensity exercise or recovery.     

A protocol for monitoring soft tissue motion under compression garments during drop landings

This study used a single-subject design to establish a valid and reliable protocol for monitoring soft tissue motion under compression garments during drop landings. One male participant performed six 40 cm drop landings onto a force platform, in three compression conditions (none, medium high). Five reflective markers placed on the thigh under the compression garment and five over the garment were filmed using two cameras (1000 Hz). Following manual digitisation, marker coordinates were reconstructed and their resultant displacements and maximum change in separation distance between skin and garment markers were calculated. To determine reliability of marker application, 35 markers were attached to the thigh over the high compression garment and filmed. Markers were then removed and re-applied on three occasions; marker separation and distance to thigh centre of gravity were calculated. Results showed similar ground reaction forces during landing trials. Significant reductions in the maximum change in separation distance between markers from no compression to high compression landings were reported. Typical errors in marker movement under and over the garment were 0.1mm in medium and high compression landings. Re-application of markers showed mean typical errors of 1mm in marker separation and <3mm relative to thigh centre of gravity. This paper presents a novel protocol that demonstrates sufficient sensitivity to detect reductions in soft tissue motion during landings in high compression garments compared to no compression. Additionally, markers placed under or over the garment demonstrate low variance in movement, and the protocol reports good reliability in marker re-application.     

Effect of magnesium lactate dihydrate and calcium lactate monohydrate on 20-km cycling time trial performance

Manufacturers of supplements containing magnesium lactate dihydrate and calcium lactate monohydrate claim improved athletic performance. Although energy can be produced through the lactate shuttle system, there is limited evidence to suggest that substantial quantities are available for human movement during exercise. The purpose of this study was to evaluate the effectiveness of lactate as a performance-enhancing substance. Nine recreational to competitive cyclists (VO2max = 52.46 ± 11.8) completed 3 simulated 20-km time trials conducted on a Velotron. The first trial was used as a familiarization trial, and the last 2 trials were counterbalanced ergogenic aid/placebo trials. To eliminate the possibility of bias, the study was conducted double blind. Dependent measures (time, mean power, heart rate [HR], and ratings of perceived exertion) for the 3 trials were compared using repeated measures analysis of variance (p = 0.05). There were no significant differences between placebo and ergogenic aid in measures of time (38.78 ± 5.87 minutes vs. 39.07 ± 6.00 minutes; p = 0.212), mean power (236.40 ± 74.8 W vs. 232.81 ± 76.12 W; p = 0.342), and HR (167.36 ± 10.11 minutes vs. 163.70 ± 13.07 minutes; p = 0.092). Ratings of perceived exertion for the placebo trial were significantly higher in relation to the ergogenic aid trial (15.97 ± 0.72 vs. 15.70 ± 0.85; p = 0.039). Although not significant, times during the placebo trials were faster in relation to the ergogenic aid trials. Ratings of perceived exertion were significantly higher in the placebo trials, which could reflect the trend toward faster times. Supplementation of magnesium lactate dihydrate and calcium lactate monohydrate does not appear to significantly improve times during a simulated 20-km time trial and therefore should not be recommended for use as an ergogenic aid.     

Effects of wearing a cooling vest during the warm-up on 10-km run performance

The purpose of this study was to examine whether wearing a cooling vest during an active warm-up would improve the 10-km time trial (TT) performance of endurance runners. Seven male runners completed 3 10-km TTs (1 familiarization and 2 experimental) on a treadmill after a 30-minute warm-up. During the warm-up of the experimental TTs, runners wore either a t-shirt (control [C]) or a cooling vest (V), the order of which was randomized. No differences were found between the C and V conditions for the 10-km TT times (2,533 ± 144 and 2,543 ± 149 seconds, respectively) (p = 0.746) or any of the 2-km split times. Heart rate (HR) at the start of the TT equaled 90 ± 17 b·min for C and 94 ± 16 b·min for V. The HR peaked at 184 ± 20 b·min in C and 181 ± 19 b·min in V. At the start of the TT Tc was 37.65 ± .72°C in C and 37.29 ± .73°C in V (p = 0.067). In C, Tc gradually increased until 39.34 ± 0.43°C while in V is reached 39.18 ± 0.72°C (p = 0.621). Although rating of perceived exertion (RPE) and Thermal sensation (TS) increased during both experimental TTs, there were no differences between V and C. Findings suggest wearing a cooling vest during a warm-up does not improve 10-km performance. The use of cooling vests during the warm-up did not produce any physiological (HR and Tc) or psychological (RPE and TS) benefit, perhaps accounting for the lack of improvement.     

The effects of a transcontinental flight on markers of coagulation and fibrinolysis in healthy men after vigorous physical activity

Purpose: Athletes and military service members are known to undergo strenuous exercise and sometimes have to take long haul flights soon afterwards; however, its combined effect on many physiological functions is relatively unknown. Therefore, we examined the combined effects of a full-body muscle-damaging workout and transcontinental flight on coagulation and fibrinolysis in healthy, resistance trained men. We also determined the efficacy of a full-body compression garment in limiting their coagulation responses. Materials and Methods: Nineteen healthy, resistance trained men flew from Connecticut (CT) to California (CA), performed a full-body muscle-damaging workout and then flew back to CT. Ten participants wore full-body compression garments (FCG) for the duration of both flights and during all other portions of the study except during workouts and blood draws, when they wore loose clothing. Nine controls wore loose clothing (CON) throughout the study. Blood samples were collected at 16 h and 3 h before the initial flight from CT, immediately after landing in CA, immediately before and immediately after the full-body workout in CA, immediately after landing in CT, and at 29 h after landing in CT. Plasma markers of coagulation included activated partial thromboplastin time (aPTT), prothrombin fragment 1+2 (PTF 1+2) and thrombin ant-thrombin (TAT). Markers of the fibrinolytic system included the tissue plasmigen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and D-Dimer. Results: Both FCG and CON groups exhibited a faster aPTT after the full-body workout compared to all other time points. Thrombin generation markers, TAT and PTF 1+2, increased significantly after the full-body workout and immediately after landing in CT. Additionally, tPA increased after the full-body workout, while PAI-1 increased before the flight to CA, after the full-body workout, and just after landing in CT. The D-Dimer significantly increased after the full-body workout and at 29 h post-flight in both groups. Between groups, aPTT was significantly faster and TAT elevated with the CON group at 29 h post-flight. Also, PAI-1 demonstrated higher concentrations immediately after landing in CT for the CON group. Conclusion: A full-body muscle-damaging workout in conjunction with a trans-continental flight activated the coagulation and fibrinolytic systems. Additionally, wearing a full-body compression garment may limit coagulation following a workout through the recovery period.     

Effects of compression on muscle tissue oxygenation at the onset of exercise

The effects of compression on gastrocnemius medialis muscle oxygenation and hemodynamics during a short-term dynamic exercise was investigated in a sample of 15 male subjects (mean ± SD; age 25.8 ± 4.9 years; mass 70.6 ± 4.3 kg). Elastic compression sleeves were used to apply multiple levels of compression to the calf muscles during exercise, and noncompressive garments were used for the control condition. Tissue hemoglobin oxygen saturation was measured as the relative "tissue oxygen index" (TOI) with a near-infrared spectrometer. The recovery of TOI during exercise was determined from the slope of oxygenation recovery in a nonoccluded situation. The TOI recovery rate during the first 2 minutes of the exercise was 24% higher (p = 0.042) for the compression condition than for the control condition. A significant correlation (r = 0.61, p = 0.012) between the level of compression and the tissue oxygenation recovery during exercise was observed. Muscle energy use was determined from the rate of decline of TOI immediately upon arterial occlusion during early exercise. Muscle energy use measured during the occluded situation was not significantly influenced by compression. Based on these results, it was concluded that compression induced changes in tissue blood flow and perfusion appear to result in improved oxygenation during short-term exercise. Assuming that increased muscle oxygen availability positively influences performance, compression of muscles may enhance performance especially in sports that require repeated short bouts of exercise.     

The effectiveness of hand cooling at reducing exercise-induced hyperthermia and improving distance-race performance in wheelchair and able-bodied athletes.

The purpose of this study was to examine the effectiveness of reducing core temperature in postexercise hyperthermic subjects and to assess if hand cooling (HC) improves subsequent timed distance performance. Following a detailed measurement check on the use of insulated auditory canal temperature (T(ac)), eight wheelchair (WA) athletes and seven male able-bodied (AB) athletes performed two testing sessions, comprising a 60-min exercise protocol and 10-min recovery period, followed by a performance trial (1 km and 3 km for WA and AB, respectively) at 30.8 degrees C (SD 0.2) and 60.6% (SD 0.2) relative humidity. In a counterbalanced order, HC and a no-cooling condition was administered during the 10-min recovery period before the performance trial. Nonsignificant condition x time interactions for both WA (F(15,75) = 1.5, P = 0.14) and AB (F(15,90) = 1.2, P = 0.32) confirmed that the exercise-induced changes (Delta) in T(ac) were similar before each intervention. However, the exercise-induced increase was evidently greater in AB compared with WA (2.0 vs. 1.3 degrees C change, respectively). HC produced DeltaT(ac) of -0.4 degrees C (SD 0.4) and -1.2 degrees C (SD 0.2) in comparison (WA and AB, respectively), and simple-effects analyses suggested that the reductions in T(ac) were noteworthy after 4 min of HC. HC had an impact on improving AB performances by -4.0 s (SD 11.5) (P < 0.05) and WA by -20.5 s (SD 24.2) (P > 0.05). In conclusion, extraction of heat through the hands was effective in lowering T(ac) in both groups and improving 3-km performance in the AB athletes and trends toward positive gains for the 1-km performance times of the WA group.     

Cerebral autoregulation dynamics in endurance-trained individuals

Aerobic fitness may be associated with reduced orthostatic tolerance. To investigate whether trained individuals have less effective regulation of cerebral vascular resistance, we studied the middle cerebral artery (MCA) mean blood velocity (V(mean)) response to a sudden drop in mean arterial pressure (MAP) after 2.5 min of leg ischemia in endurance athletes and untrained subjects (maximal O(2) uptake: 69 ± 7 vs. 42 ± 5 ml O(2)·min(-1)·kg(-1); n = 9 for both, means ± SE). After cuff release when seated, endurance athletes had larger drops in MAP (94 ± 6 to 62 ± 5 mmHg, -39%, vs. 99 ± 5 to 73 ± 4 mmHg, -26%) and MCA V(mean) (53 ± 3 to 37 ± 2 cm/s, -30%, vs. 58 ± 3 to 43 ± 2 cm/s, -25%). The athletes also had a slower recovery to baseline of both MAP (25 ± 2 vs. 16 ± 1 s, P < 0.01) and MCA V(mean) (15 ± 1 vs. 11 ± 1 s, P < 0.05). The onset of autoregulation, determined by the time point of increase in the cerebrovascular conductance index (CVCi = MCA V(mean)/MAP) appeared later in the athletes (3.9 ± 0.4 vs. 2.7 ± 0.4s, P = 0.01). Spectral analysis revealed a normal MAP-to-MCA V(mean) phase in both groups but ~40% higher normalized MAP to MCA V(mean) low-frequency transfer function gain in the trained subjects. No significant differences were detected in the rates of recovery of MAP and MCA V(mean) and the rate of CVCi regulation (18 ± 4 vs. 24 ± 7%/s, P = 0.2). In highly trained endurance athletes, a drop in blood pressure after the release of resting leg ischemia was more pronounced than in untrained subjects and was associated with parallel changes in indexes of cerebral blood flow. Once initiated, the autoregulatory response was similar between the groups. A delayed onset of autoregulation with a larger normalized transfer gain conforms with a less effective dampening of MAP oscillations, indicating that athletes may be more prone to instances of symptomatic cerebral hypoperfusion when MAP declines.     

The effects of skin pressure by clothing on circadian rhythms of core temperature and salivary melatonin

The present experiment investigated the effects of skin pressure by foundation garments (girdle and brassiere) on the circadian rhythms of core temperature and salivary melatonin. Ten healthy females (18-23 years) maintained regular sleep-wake cycles for a week prior to participation in the experiment. The experiments were performed from June to August 1999 using a bioclimatic chamber controlled at 26.5 degrees C +/- 0.2 degrees C and 62% +/- 3% RH. Ambient light intensity was controlled at 500 lux from 07:30 to 17:30, 100 lux from 17:30 to 19:30, 20 lux from 19:30 to 23:30; there was total darkness from 23:30 to 07:30. The experiment lasted for 58h over three nights. The participants arose at 07:30 on the first full day and retired at 23:30, adhering to a set schedule for 24h, but without wearing foundation garments. For the final 24h of the second full day, the subjects wore foundation garments. Rectal and leg skin temperatures were measured continuously throughout the experiment. Saliva and urine were collected every 4h for the analysis of melatonin and catecholamines, respectively. Skin pressure applied by the foundation garments was in the range 11-17 gf/cm2 at the regions of the abdomen, hip, chest, and back. The main results were as follows: (1) Rectal temperatures were significantly higher throughout the day and night when wearing foundation garments. (2) The nocturnal level of salivary melatonin measured at 03:30 was 115.2 +/- 40.4 pg/mL (mean +/- SEM, N = 10) without and 51.3 +/- 18.4 pg/mL (mean +/- SEM, N = 10) with foundation garments. (3) Mean urinary noradrenaline excretion was significantly lower throughout the day and night when wearing foundation garments (p < .05), but mean urinary adrenaline excretion was not different. The results suggest that skin pressure by clothing could markedly suppress the nocturnal elevation of salivary melatonin, resulting in an increase of rectal temperature.     

Sun-dried raisins are a cost-effective alternative to Sports Jelly Beans in prolonged cycling

The purpose of this study was to examine the effects of a natural carbohydrate (CHO) source in the form of sun-dried raisins (SDRs) vs. Sports Jelly Beans? (SJBs) on endurance performance in trained cyclists and triathletes. Ten healthy men (18-33 years) completed 1 water-only acclimatization exercise trial and 2 randomized exercise trials administered in a crossover fashion. Each trial consisted of a 120-minute constant-intensity glycogen depletion period followed by a 10-km time trial (TT). During each experimental trial, participants consumed isocaloric amounts of SDRs or SJBs in 20-minute intervals. Measurements included time to complete 10-km TT, power output during 10-km TT, blood glucose levels and respiratory exchange ratio during glycogen depletion period, rate of perceived exertion (RPE), 'flow' questionnaire responses, and a hedonic (i.e., pleasantness) sensory acceptance test. There were no significant differences in endurance performance for TT time (SDRs vs. SJBs, 17.3 ± 0.4 vs. 17.3 ± 0.4 seconds) or power (229.3 ± 13.0 vs. 232.0 ± 13.6 W), resting blood glucose levels (5.8 ± 04 mmol·L(-1) for SDRs and 5.4 ± 0.2 mmol·L(-1) for SJBs), RPE, or flow experiences between SDR and SJB trials. However, the mean sensory acceptance scores were significantly higher for the SDRs compared to the SJBs (50.7 ± 1.7 vs. 44.3 ± 2.7). Consuming SDRs or SJBs during 120 minutes of intense cycling results in similar subsequent TT performances and are equally effective in maintaining blood glucose levels during exercise. Therefore, SDRs are a natural, pleasant, cost-effective CHO alternative to commercial SJBs that can be used during moderate- to high-intensity endurance exercise.     

Examining the influence of hydration status on physiological responses and running speed during trail running in the heat with controlled exercise intensity

The purpose of this study was to determine the effects of dehydration at a controlled relative intensity on physiological responses and trail running speed. Using a randomized, controlled crossover design in a field setting, 14 male and female competitive, endurance runners aged 30 ± 10.4 years completed 2 (hydrated [HY] and dehydrated [DHY]) submaximal trail runs in a warm environment. For each trial, the subjects ran 3 laps (4 km per lap) on trails with 4-minute rests between laps. The DHY were fluid restricted 22 hours before the trial and during the run. The HY arrived euhydrated and were given water during rest breaks. The subjects ran at a moderate pace matched between trials by providing pacing feedback via heart rate (HR) throughout the second trial. Gastrointestinal temperature (T(GI)), HR, running time, and ratings of perceived exertion (RPE) were monitored. Percent body mass (BM) losses were significantly greater for DHY pretrial (-1.65 ± 1.34%) than for HY (-0.03 ± 1.28%; p < 0.001). Posttrial, DHY BM losses (-3.64 ± 1.33%) were higher than those for HY (-1.38 ± 1.43%; p < 0.001). A significant main effect of T(GI) (p = 0.009) was found with DHY having higher T(GI) postrun (DHY: 39.09 ± 0.45°C, HY: 38.71 ± 0.45°C; p = 0.030), 10 minutes post (DHY: 38.85 ± 0.48°C, HY: 38.46 ± 0.46°C; p = 0.009) and 30 minutes post (DHY: 38.18 ± 0.41°C, HY: 37.60 ± 0.25°C; p = 0.000). The DHY had slower run times after lap 2 (p = 0.019) and lap 3 (p = 0.025). The DHY subjects completed the 12-km run 99 seconds slower than the HY (p = 0.027) subjects did. The RPE in DHY was slightly higher than that in HY immediately postrun (p = 0.055). Controlling relative intensity in hypohydrated runners resulted in slower run times, greater perceived effort, and elevated T(GI), which is clinically meaningful for athletes using HR as a gauge for exercise effort and performance.     

Iron supplementation improves endurance after training in iron-depleted, nonanemic women.

Our objective was to investigate the effects of iron depletion on adaptation to aerobic exercise, assessed by time to complete a 15-km cycle ergometer test. Forty-two iron-depleted (serum ferritin <16 microg/l), nonanemic (Hb >12 g/dl) women (18-33 yr old) received 100 mg of ferrous sulfate (S) or placebo (P) per day for 6 wk in a randomized, double-blind trial. Subjects trained for 30 min/day, 5 days/wk at 75-85% of maximum heart rate for the final 4 wk of the study. There were no group differences in baseline iron status or in 15-km time. Iron supplementation increased serum ferritin and decreased transferrin receptors in the S compared with the P group. The S and P groups decreased 15-km time and respiratory exchange ratio and increased work rate during the 15-km time trial after training. The decrease in 15-km time was greater in the S than in the P group (P = 0.04) and could be partially attributed to increases in serum ferritin and Hb. These results indicate that iron deficiency without anemia impairs favorable adaptation to aerobic exercise.     

THE EFFECTS OF SKIN PRESSURE BY CLOTHING ON CIRCADIAN RHYTHMS OF CORE TEMPERATURE AND SALIVARY MELATONIN

The present experiment investigated the effects of skin pressure by foundation garments (girdle and brassiere) on the circadian rhythms of core temperature and salivary melatonin. Ten healthy females (18–23 years) maintained regular sleep-wake cycles for a week prior to participation in the experiment. The experiments were performed from June to August 1999 using a bioclimatic chamber controlled at 26.5°C ± 0.2°C and 62% ± 3% RH. Ambient light intensity was controlled at 500 lux from 07:30 to 17:30, 100 lux from 17:30 to 19:30, 20 lux from 19:30 to 23:30; there was total darkness from 23:30 to 07:30. The experiment lasted for 58h over three nights. The participants arose at 07:30 on the first full day and retired at 23:30, adhering to a set schedule for 24h, but without wearing foundation garments. For the final 24h of the second full day, the subjects wore foundation garments. Rectal and leg skin temperatures were measured continuously throughout the experiment. Saliva and urine were collected every 4h for the analysis of melatonin and catecholamines, respectively. Skin pressure applied by the foundation garments was in the range 11–17 gf/cm² at the regions of the abdomen, hip, chest, and back. The main results were as follows: (1) Rectal temperatures were significantly higher throughout the day and night when wearing foundation garments. (2) The nocturnal level of salivary melatonin measured at 03:30 was 115.2 ± 40.4 pg/mL (mean ± SEM, N = 10) without and 51.3 ± 18.4 pg/mL (mean ± SEM, N = 10) with foundation garments. (3) Mean urinary noradrenaline excretion was significantly lower throughout the day and night when wearing foundation garments (p <. 05), but mean urinary adrenaline excretion was not different. The results suggest that skin pressure by clothing could markedly suppress the nocturnal elevation of salivary melatonin, resulting in an increase of rectal temperature. (Chronobiology International, 17(6) 783–793, 2000)     

Recovery effects of hyperoxic gas inhalation or contrast water immersion on the postexercise cytokine response, perceptual recovery, and next day exercise performance

The effect of different recovery modalities on the postexercise cytokine response, perceptual recovery, and subsequent day athletic performance were investigated. Eight highly trained athletes completed 3 swimming sessions consisting of 20 × 200 m efforts, in a counterbalanced repeated-measures design. At the conclusion of each session, athletes undertook a 30-minute recovery intervention of contrast water therapy (CWT), supplemental oxygen (HYP), or passive rest (CON). Venous blood samples were analyzed for levels of interleukin-6 (IL-6) at the pre-, post-, and 30-minute postswim time points, and a rating of perceived recovery was recorded at the conclusion of the 30-minute intervention and upon returning to the pool 12 hour later. Finally, a 200-m swim time trial was completed as a measure of next day performance. The results showed that there was a significant increase in IL-6 at the completion of exercise, which persisted after 30 minutes of recovery (p < 0.05), with no differences evident between the groups. Additionally, the perception of recovery after the 30-minute intervention was significantly lower in the CON when compared with the CWI and HYP (p < 0.05). However, there were no differences in the 12-hour postrecovery time trial performances. These results suggest that a 30-minute recovery intervention using CWT or HYP has limited influence on the acute-phase response or on improving subsequent day athletic performance. However, strength and conditioning specialists should encourage the use of a structured postexercise recovery procedure because the evidence suggests that the acute perception of recovery is much greater when some form of intervention is implemented in comparison with no recovery procedure at all.     

Long-term effects of graduated compression stockings on cardiorespiratory performance

The use of graduated compression stockings (GCS) in sport has been increasing in the last years due to their potential positive effects for athletes. However, there is little evidence to support whether these types of garments actually improve cardiorespiratory performance. The aim of this study was to examine the cardiorespiratory responses of GCS during running after three weeks of regular use. Twenty recreational runners performed three tests on different days: test 1) – a 5-min maximal effort run in order to determine the participants’ maximal aerobic speed; and tests 2) and 3) – a fatigue running test of 30 minutes at 80% of their maximal aerobic speed with either GCS or PLACEBO stockings at random. Cardiorespiratory parameters (minute ventilation, heart rate, relative oxygen consumption, relative carbon dioxide production, ventilatory equivalents for oxygen and carbon dioxide, and oxygen pulse) were measured. Before each test in the laboratory, the participants trained with the randomly assigned stockings (GCS or PLACEBO) for three weeks. No significant differences between GCS and PLACEBO were found in any of the cardiorespiratory parameters. In conclusion, the present study provides evidence that running with GCS for three weeks does not influence cardiorespiratory parameters in recreational runners.     

The influence of parachute-resisted sprinting on running mechanics in collegiate track athletes

The influence of parachute-resisted sprinting on running mechanics in collegiate track athletes. The aim of this investigation was to compare the acute effects of parachute-resisted (PR) sprinting on selected kinematic variables. Twelve collegiate sprinters (mean age 19.58 ± 1.44 years, mass 69.32 ± 14.38 kg, height 1.71 ± 9.86 m) ran a 40-yd dash under 2 conditions: PR sprint and sprint without a parachute (NC) that were recorded on a video computer system (60 Hz). Sagittal plane kinematics of the right side of the body was digitized to calculate joint angles at initial ground contact (IGC) and end ground contact (EGC), ground contact (GC) time, stride rate (SR), stride length (SL), and the times of the 40-yd dashes. The NC 40-yd dash time was significantly faster than the PR trial (p < 0.05). The shoulder angle at EGC significantly increased from 34.10 to 42.10° during the PR trial (p < 0.05). There were no significant differences in GC time, SR, SL, or the other joint angles between the 2 trials (p > 0.05). This study suggests that PR sprinting does not acutely affect GC time, SR, SL and upper extremity or lower extremity joint angles during weight acceptance (IGC) in collegiate sprinters. However, PR sprinting increased shoulder flexion by 23.5% at push-off and decreased speed by 4.4%. While sprinting with the parachute, the athlete's movement patterns resembled their mechanics during the unloaded condition. This indicates the external load caused by PR did not substantially overload the runner, and only caused a minor change in the shoulder during push-off. This sports-specific training apparatus may provide coaches with another method for training athletes in a sports-specific manner without causing acute changes to running mechanics.