The effect of three recovery protocols on blood lactate clearance after race-paced swimming

ABSTRACT: Lomax, M. The effect of three recovery protocols on blood lactate clearance after race-paced swimming. J Strength Cond Res 26(10): 2771-2776, 2012-The purpose of the present study was to assess the impact of 3 recovery protocols on blood lactate clearance after maximal intensity swimming. Thirty-three regional standard swimmers were tested throughout the course a year and were required to complete a race-paced 200-m swim in their main stroke or individual medley. After the race-paced swim, swimmers were assigned a self-paced continuous steady rate swim of 20 minutes (self-prescribed); a 20-minute coach-administered modified warm-up consisting of various swimming modes, intensities, and rest intervals (coach prescribed); or a 20-minute land-based recovery consisting of light-intensity walking, skipping, and stretching (land based). Blood lactate concentration was measured from the fingertip before and after the race-paced swim and after the recovery activity. The concentration of blood lactate was higher (p < 0.01) after race-paced swimming (range of 10.5-11.0 mmol·L) compared with baseline (range 1.3-1.4 mmol·L). However, there were no differences (p > 0.05) between the groups (recovery protocols) at these time points. Conversely, differences were observed between groups after the recovery activities (p < 0.01). Specifically, blood lactate concentration was higher after the land-based activity (3.7 ± 1.8 mmol·L) than either the self-prescribed (2.0 ± 1.2 mmol·L) or coach-prescribed (1.8 ± 0.9 mmol·L) swimming protocols. The results of the present study suggest that it does not matter whether a self-paced continuous steady rate swimming velocity or a swimming recovery consisting of various strokes, intensities, and rest intervals is adopted as a recovery activity. As both swimming recoveries removed more blood lactate than the land-based recovery, swimmers should therefore be advised to undertake a swimming-based recovery rather than a land-based recovery.     

Benefits of caffeine ingestion on sprint performance in trained and untrained swimmers

The influence of specific training on benefits from caffeine (Caf) ingestion was examined during a sprint test in a group of highly trained swimmers (T) and compared with the response of a group of untrained occasional swimmers (UT). Seven T and seven UT subjects swam freestyle two randomly assigned 2 x 100 m distances, at maximal speed and separated by 20 min of passive recovery, once after Caf (250 mg) and once after placebo (Pla) ingestion. Anaerobic capacity was assessed by the mean velocity (meters per second) during each 100 m and blood was sampled from the fingertip just before and 1, 3, 5, 7, and 9 min after each 100 m for resting and maximal blood lactate concentration ([la-]b,max) determination. The [la-]bmax was significantly enhanced by Caf in both T and UT subjects (P less than 0.01). However, only T subjects exhibited significant improvement in their swimming velocity (P less than 0.01) after Caf or any significant impairment during the second 100 m. In light of these results, it appears that specific training is necessary to benefit from the metabolic adaptations induced by Caf during supramaximal exercise requiring a high anaerobic capacity.     

Effects of 4 weeks of creatine supplementation in junior swimmers on freestyle sprint and swim bench performance

To determine whether 4 weeks of oral creatine (Cr) supplementation could enhance single freestyle sprint and swim bench performance in experienced competitive junior swimmers, 10 young men and 10 young women (x age = 16.4 +/- 1.8 years) participated in a 27-day supplementation period and pre- and posttesting sessions. In session 1 (presupplementation testing), subjects swam one 50-m freestyle and then (after approximately 5 minutes of active recovery) one 100-m freestyle at maximum speed. Blood lactate was measured before and 1 minute after each swim trial. Forty-eight hours later, height, mass, and the sum of 6 skinfolds were recorded, and a Biokinetic Swim Bench total work output test (2 x 30-second trials, with a 10-minute passive recovery in between) was undertaken. After the pretests were completed, participants were divided into 2 groups (n = 10, Cr; and n = 10, placebo) by means of matched pairs on the basis of gender and 50-m swim times. A Cr loading phase of 20 g x d(-1) for 5 days was then instituted, followed by a maintenance phase of 5 g x d(-1) for 22 days. Postsupplementation testing replicated the presupplementation tests. Four weeks of Cr supplementation did not influence single sprint performance in the pool or body mass and composition. However, 30-second swim bench total work scores for trial 1 and trial 2 increased after Cr (p < 0.05) but not placebo ingestion. Postexercise blood lactate values were not different after supplementation for the 50- and 100-m sprint trials either within or between groups. It was concluded that 4 weeks of Cr supplementation did not significantly improve single sprint performance in competitive junior swimmers, but it did enhance swim bench test performance.     

Performance and physiological responses to a 5-week synchronized swimming technical training programme in humans

A synchronized swimming team routine (TR) is composed of figures of varying degrees of difficulty. Swimmers able to perform these figures separately underwent a 5-week technical training programme (TTP) to assemble a TR. Little is known about the physiological responses to this kind of TTP. A group of 13 trained synchronized swimmers [mean age 14 (SD 1) years] were tested before and after a 5-week TTP. The TR lasted 5 min, and 45% of that time was spent underwater. The swimmers' technique scores in the TR improved significantly from 4.5 (SD 1.9) before to 5.8 (SD 2.3) points after the TTP (P < 0.01), but their swimming performances, peak oxygen uptake (VO2peak), blood lactate concentration, and heart rate measured during a 400-m swim were lower after the TTP. The improvement in the technique scores correlated negatively with the change in VO2peak (r = -0.57; P < 0.05). The greater the improvement in the technique score, the greater the decrease in VO2peak. The overall synchronized swimming skill was assessed by the best score the swimmers obtained in four to six competitions over a season. This score was related to the 400-m swimming performance, VO2peak, maximal distance covered in apnoea, and the breath-hold time. The 5-week TTP therefore improved technical performance during the TR without improving physiological, swimming or apnoea performances. However, the physiological profile of each swimmer was linked to the synchronized swimming skill.     

Effect of recovery mode on repeated sprint ability in young basketball players

The aim of this study was to examine the effect of recovery mode on repeated sprint ability in young basketball players. Sixteen basketball players (age, 16.8 +/- 1.2 years; height, 181.3 +/- 5.7 cm; body mass, 73 +/- 10 kg; VO2max, 59.5 +/- 7.9 mL x kg(-1) x min(-1)) performed in random order over 2 separate occasions 2 repeated sprint ability protocols consisting of 10 x 30-m shuttle run sprints with 30 seconds of passive or active (running at 50% of maximal aerobic speed) recovery. Results showed that fatigue index (FI) during the active protocol was significantly greater than in the passive condition (5.05 +/- 2.4, and 3.39 +/- 2.3, respectively, p < 0.001). No significant association was found between VO2peak and FI and sprint total time (TT) in either repeated sprint protocols. Blood lactate concentration at 3 minutes post exercise was not significantly different between the 2 recovery conditions. The results of this study show that during repeated sprinting, passive recovery enabled better performance, reducing fatigue. Consequently, the use of passive recovery is advisable during competition in order to limit fatigue as a consequence of repeated high intensity exercise.     

Lactate threshold and performance adaptations to 4 weeks of training in untrained swimmers: volume vs. intensity

The purpose of this study was to investigate the impact of 4 weeks of high-intensity vs. high-volume swim training on lactate threshold (LT) characteristics and performance. Thirteen untrained swimmers with a mean age of 19.0 ± 0.5 undertook an incremental swimming test before and after 4 weeks of training for the determination of LT. Performance was evaluated by a 50-m maximum freestyle test. The swimmers were assigned to 1 of each of 2 training groups. The high-intensity group (n = 6) focused on sprint training (SP) and swam a total of 1,808 ± 210 m. The high-volume group (n = 7) followed the same program as the SP group but swam an additional 1,100 m (38% more) of endurance swimming (SP + End). A training effect was evident in both groups as seen by the similar improvements in sprint performance of the 50-m maximum time (p < 0.01), peak velocity increases and the lower value of lactate at the individual LTs (p < 0.01). Lactate threshold velocity improved only in the SP + End group from 1.20 ± 0.12 m·s(-1) pretraining to 1.32 ± 0.12 m·s(-1) posttraining (p = 0.77, effect size = 1, p < 0.01), expressed by the rightward shifts of the individual lactate-velocity curves, indicating an improvement in the aerobic capacity. Peak lactate and lactate concentrations at LT did not significantly change. In conclusion, this study was able to demonstrate that 4 weeks of either high-intensity or high-volume training was able to demonstrate similar improvements in swimming performance. In the case of lack of significant changes in lactate profiling in response to high-intensity training, we could suggest a dissociation between the 2.     

Diurnal variation and reliability of the urine lactate concentration after maximal exercise

The postexercise urine lactate concentration is a novel valid exercise biomarker, which has exhibited satisfactory reliability in the morning hours under controlled water intake. The aim of the present study was to investigate the diurnal variation of the postexercise urine lactate concentration and its reliability in the afternoon hours. Thirty-two healthy children (11 boys and 21 girls) and 23 adults (13 men and 10 women) participated in the study. All participants performed two identical sessions of eight 25 m bouts of maximal freestyle swimming executed every 2 min with passive recovery in between. These sessions were performed in the morning and afternoon and were separated by 3–4 days. Adults performed an additional afternoon session that was also separated by 3–4 days. All swimmers drank 500 mL of water before and another 500 mL after each test. Capillary blood and urine samples were collected before and after each test for lactate determination. Urine creatinine, urine density and body water content were also measured. The intraclass correlation coefficient was used as a reliability index between the morning and afternoon tests, as well as between the afternoon test and retest. Swimming performance and body water content exhibited excellent reliability in both children and adults. The postexercise blood lactate concentration did not show diurnal variation, showing a good reliability between the morning and afternoon tests, as well as high reliability between the afternoon test and retest. The postexercise urine density and lactate concentration were affected by time of day. However, when lactate was normalized to creatinine, it exhibited excellent reliability in children and good-to-high reliability in adults. The postexercise urine lactate concentration showed high reliability between the afternoon test and retest, independent of creatinine normalization. The postexercise blood and urine lactate concentrations were significantly correlated in all cases, attesting to the validity of urine lactate as an index of anaerobic metabolism. We conclude that urine lactate, after normalization to creatinine, could be used in training practice either in the morning or in the afternoon. Further research is needed to assess the applicability of this novel exercise biomarker.     

Sodium bicarbonate ingestion improves performance in interval swimming

In an effort to determine the effects of bicarbonate (NaHCO3) ingestion on exercise performance, ten male college swimmers were studied during five different trials. Each trial consisted of five 91.4 m (100-yd) front crawl swims with a two-minute rest interval between each bout. The trials consisted of two NaHCO3 treatments, two placebo trials and one test with no-drink. One hour before the onset of swimming, the subjects were given 300 ml of citric acid flavored solution containing either 17 mmol of NaCl (placebo) or 2.9 mmol of NaHCO3.kg-1 body weight (experimental), or received no drink (no-drink). Performance times for each 91.4 m swim were recorded. Blood samples were obtained before and one hr after treatment, two min after warmup, and two min after the final 91.4 m sprint. Blood pH, lactate, standard bicarbonate (SBC) and base excess (BE) were measured. No differences were found for performance or the blood measurements between the placebo and no-drink trials. Bicarbonate feedings, on the other hand, produced a significant (P less than 0.05) improvement in performance on the fourth and fifth swimming sprints. Blood lactate, pH, SBC and BE were significantly higher (P less than 0.05) at post-exercise in NaHCO3 treatments. These data are in agreement with previous findings that during repeated bouts of exercise pre-exercise administration of NaHCO3 improves performance, possibly by facilitating the efflux of hydrogen ions from working muscles and thereby delaying the onset of fatigue.     

Growth hormone responses to repeated maximal cycle ergometer exercise at different pedaling rates.

The present study examined the growth hormone (GH) response to repeated bouts of maximal sprint cycling and the effect of cycling at different pedaling rates on postexercise serum GH concentrations. Ten male subjects completed two 30-s sprints, separated by 1 h of passive recovery on two occasions, against an applied resistance equal to 7.5% (fast trial) and 10% (slow trial) of their body mass, respectively. Blood samples were obtained at rest, between the two sprints, and for 1 h after the second sprint. Peak and mean pedal revolutions were greater in the fast than the slow trial, but there were no differences in peak or mean power output. Blood lactate and blood pH responses did not differ between trials or sprints. The first sprint in each trial elicited a serum GH response (fast: 40.8 +/- 8.2 mU/l, slow: 20.8 +/- 6.1 mU/l), and serum GH was still elevated 60 min after the first sprint. The second sprint in each trial did not elicit a serum GH response (sprint 1 vs. sprint 2, P < 0.05). There was a trend for serum GH concentrations to be greater in the fast trial (mean GH area under the curve after sprint 1 vs. after sprint 2: 1,697 +/- 367 vs. 933 +/- 306 min x mU(-1) x l(-1); P = 0.05). Repeated sprint cycling results in an attenuation of the GH response.     

Human power output during repeated sprint cycle exercise: the influence of thermal stress

Thermal stress is known to impair endurance capacity during moderate prolonged exercise. However, there is relatively little available information concerning the effects of thermal stress on the performance of high-intensity short-duration exercise. The present experiment examined human power output during repeated bouts of short-term maximal exercise. On two separate occasions, seven healthy males performed two 30-s bouts of sprint exercise (sprints I and II), with 4 min of passive recovery in between, on a cycle ergometer. The sprints were performed in both a normal environment [18.7 (1.5) degrees C, 40 (7)% relative humidity (RH; mean SD)] and a hot environment [30.1 (0.5) degrees C, 55 (9)% RH]. The order of exercise trials was randomised and separated by a minimum of 4 days. Mean power, peak power and decline in power output were calculated from the flywheel velocity after correction for flywheel acceleration. Peak power output was higher when exercise was performed in the heat compared to the normal environment in both sprint I [910 (172) W vs 656 (58) W; P < 0.01] and sprint II [907 (150) vs 646 (37) W; P < 0.05]. Mean power output was higher in the heat compared to the normal environment in both sprint I [634 (91) W vs 510 (59) W; P < 0.05] and sprint II [589 (70) W vs 482 (47) W; P < 0.05]. There was a faster rate of fatigue (P < 0.05) when exercise was performed in the heat compared to the normal environment. Arterialised-venous blood samples were taken for the determination of acid-base status and blood lactate and blood glucose before exercise, 2 min after sprint I, and at several time points after sprint II. Before exercise there was no difference in resting acid-base status or blood metabolites between environmental conditions. There was a decrease in blood pH, plasma bicarbonate and base excess after sprint I and after sprint II. The degree of post-exercise acidosis was similar when exercise was performed in either of the environmental conditions. The metabolic response to exercise was similar between environmental conditions; the concentration of blood lactate increased (P < 0.01) after sprint I and sprint II but there were no differences in lactate concentration when comparing the exercise bouts performed in a normal and a hot environment. These data demonstrate that when brief intense exercise is performed in the heat, peak power output increases by about 25% and mean power output increases by 15%; this was due to achieving a higher pedal cadence in the heat.     

Blood lactate production and recovery from anaerobic exercise in trained and untrained boys

Blood lactate production and recovery from anaerobic exercise were investigated in 19 trained (AG) and 6 untrained (CG) prepubescent boys. The exercises comprised 3 maximal test performances; 2 bicycle ergometer tests of different durations (15 s and 60 s), and running on a treadmill for 23.20 +/- 2.61 min to measure maximal oxygen uptake. Blood samples were taken from the fingertip to determine lactate concentrations and from the antecubital vein to determine serum testosterone. Muscle biopsies were obtained from vastus lateralis. Recovery was passive (seated) following the 60 s test but that following the treadmill run was initially active (10 min), and then passive. Peak blood lactate was highest following the 60 s test (AG, 13.1 +/- 2.6 mmol.1-1 and CG, 12.8 +/- 2.3 mmol.1-1). Following the 15 s test and the treadmill run, peak lactate values were 68.7 and 60.6% of the 60 s value respectively. Blood lactate production was greater (p less than 0.001) during the 15 s test (0.470 +/- 0.128 mmol.1-1.s-1) than during the 60 s test (0.184 +/- 0.042 mmol.1-1.s-1). Although blood lactate production was only nonsignificantly greater in AG, the amount of anaerobic work in the short tests was markedly greater (p less than 0.05-0.01) in AG than CG. Muscle fibre area (type II%) and serum testosterone were positively correlated (p less than 0.05) with blood lactate production in both short tests. Blood lactate elimination was greater (p less than 0.001) at the end of the active recovery phase than in the next (passive) phase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gentle exercise with a previously inactive muscle group hastens the decline of blood lactate concentration after strenuous exercise

The aim of this study was to elucidate the mechanism by which the disappearance of blood lactate following severe exercise is enhanced during active recovery in comparison with recovery at rest. Rates of decline of arterialised venous blood lactate concentrations in man after maximal one-leg exercise were compared during four different modes of recovery: passive (PR), exercise of the muscles involved in the initial exercise (SL), exercise of the corresponding muscles in the hitherto-inactive leg (OL), or exercise of one arm (RA). Recovery exercise workloads were each 40% of the onset of blood lactate accumulation (OBLA) for the limb used. In comparison with PR, SL and OL accelerated the fall in blood lactate to similar extents whereas RA was without effect. The first-order rate constant (min-1) for decline of arterialised venous blood lactate concentration after the intense exercise was 0.027 (0.003) in PR, 0.058 (0.025) in SL, 0.034 (0.002) in OL, and in RA was 0.028 (0.002) [mean (SEM), n = 6 subjects]. Preliminary studies had shown that RA in isolation elevated blood lactate whereas SL and OL did not. Thus, with appropriate workloads, exercise of either hitherto active or passive muscles enhanced blood lactate decline during recovery from intense exercise. This suggests that the effect resulted principally from the uptake and utilisation of lactate in the circulation by those exercising muscles rather than from increased transport of lactate to other sites of clearance by sustained high blood flow through the previously active muscles.     

Acute cardiorespiratory responses of hypertensive rats to swimming and treadmill exercise

The acute cardiorespiratory responses of spontaneously hypertensive rats (SHR) to swimming and running exercise was investigated because SHR populations are hyperresponsive to external stimuli, of the paucity of existing data, and of the uncertainty on the role of exercise stimuli for training adaptations to occur. Male rats were assigned to one of five groups (n = 5-6/group) and designated as controls (C), inexperienced or naive free swimmers (NFS), experienced free swimmers (FS), experienced weighted swimmers (WS) (attached weights equal to 2% of their body weight) or experienced runners (R) who ran at an intensity of 75% of their VO2max. After 75 min in the water, all groups were acidotic and hypercapnic with the WS experiencing the greatest changes. Heart rate (HR) was increased in all swimmers during the initial 10 min, but declined thereafter, and after 75 min, the HR of WS (348 +/- 1 beats/min) was significantly lower than the C group (416 +/- 22 beats/min). At the same time interval, mean arterial blood pressure (MAP) was decreased in all swimming groups to values lower than the C animals. In addition, an exaggerated diving reflex was frequently noted when the rats were submerged. When the magnitudes of the changes were evaluated in the swimming animals they were directly associated with their submergence times, i.e., during 65-75 min of the swim, NFS, FS, and WS were submerged for 43, 46, and 66% of their total swim time, respectively. In sharp contrast to the swimmers, the runners exhibited increases in HR and MAP with their blood gas measurements being indicative of hyperventilation. We concluded that swimming as an exercise mode for hypertensive rats is best served to study the combined effects of excitement, prolonged submergence, and the consequences of the diving reflex.     

Combined creatine and sodium bicarbonate supplementation enhances interval swimming

This study examined the effect of simultaneous supplementation of creatine and sodium bicarbonate on consecutive maximal swims. Sixteen competitive male and female swimmers completed, in a randomized order, 2 different treatments (placebo and a combination of creatine and sodium bicarbonate) with 30 days of washout period between treatments in a double-blind crossover procedure. Both treatments consisted of placebo or creatine supplementation (20 g per day) in 6 days. In the morning of the seventh day, there was placebo or sodium bicarbonate supplementation (0.3 g per kg body weight) during 2 hours before a warm-up for 2 maximal 100-m freestyle swims that were performed with a passive recovery of 10 minutes in between. The first swims were similar, but the increase in time of the second versus the first 100-m swimming time was 0.9 seconds less (p < 0.05) in the combination group than in placebo. Mean blood pH was higher (p < 0.01-0.001) in the combination group than in placebo after supplementation on the test day. Mean blood pH decreased (p < 0.05) similarly during the swims in both groups. Mean blood lactate increased (p < 0.001) during the swims, but there were no differences in peak blood lactate between the combination group (14.9 +/- 0.9 mmol.L(-1)) and placebo (13.4 +/- 1.0 mmol.L(-1)). The data indicate that simultaneous supplementation of creatine and sodium bicarbonate enhances performance in consecutive maximal swims.     

Effects of abrupt cold shock on stress responses and recovery in brown trout exhausted by swimming

To simulate swimming in a trawl, age 3 year brown trout Salmo trutta (L.) were made to swim against a flow of 0·5 m s⁻¹ for 60 min. To simulate cold shock, similar to placing them in a chilling tank, the fish were kept for 10 min in a tank containing ice and water. To simulate the combined stressors, the fish were first made to swim followed by a cold shock. The fish were in a comatose state 10 min after cold shock and combined stressors but conscious after swimming only. All the fish survived until the end of the studied recovery period (maximum 24 h). Cold shock after swimming (combined stressors v . swimming only) did not produce higher blood cortisol, lactate or glucose concentrations 10 min after the treatment. The effect of cold shock, however, was evident in the delayed start of recovery in cortisol and glucose concentrations. All the stress indicators used decreased to the levels for undisturbed fish within 24 h, except in the case of glucose after the combined stressors.     

Continuous intramuscular pH measurement during the recovery from brief, maximal exercise in man

Muscle pH and temperature were measured before, and continuously for 30 min after, a 30-s maximal sprint exercise in ten subjects. These measurements were made with a needle-tipped pH electrode and a thermocouple placed in vastus lateralis. Venous blood samples were collected for pH, lactate and catecholamine estimations and measurements were also made of the arterial blood pressure and heart rate. The muscle and venous pH decreased from 7.17 +/- 0.01 (mean +/- SEM) and 7.39 +/- 0.01 to 6.57 +/- 0.04 and 7.04 +/- 0.03, respectively, in response to the exercise. No significant recovery occurred in either pH measurement for 10 min, after which muscle pH increased to 7.03 +/- 0.03 and venous pH to 7.29 +/- 0.01 by 30 min. Muscle temperature increased by 2.1 degrees C with exercise and also failed to return to pre-exercise values by 30 min. Blood lactate concentration increased from 0.75 +/- 0.04 mmol l-1 before exercise to a peak value of 15.76 +/- 0.35 mmol l-1 5 min after completion of the exercise, and then declined slowly to 10.30 +/- 0.61 mmol l-1 by 30 min. Arterial blood pressure increased transiently with exercise but recovered rapidly, whereas the exercise-induced tachycardia was sustained throughout the recovery period. The recovery from the metabolic and cardiovascular responses to maximal sprint exercise in man is incomplete 30 min after cessation of the exercise.     

Effects of carbon dioxide inhalation prior to maximal exercise on blood lactate and physical performance

In order to examine the effect of acute respiratory acidosis induced by CO2 inhalation prior to maximal exercise on blood lactate and physical performance, double determinations were carried out for each subject on separate days; one day, after CO2 inhalation and other day, after inhalation of room air. It was observed that in the untrained subjects the CO2 inhalation prior to maximal treadmill exercise does not affect endurance time and maximum aerobic power, whereas blood lactate during recovery was lower in CO2 breathing than that in room air. In addition, no significant difference of 200m sprint time in the athletes was noticed between CO2 and room air while blood lactate after 200m sprint running was significantly lower in the CO2 than that in room air. From these results, it was suggested that the effect of CO2 inhalation prior to maximal exercise as applied here appeared to be mediate through metabolic rather than oxygen transport mechanism, but not related to physical performance.     

Blood lactate disappearance at various intensities of recovery exercise

Numerous studies have reported that following intense exercise the rate of blood lactate (La) disappearance is greater during continuous aerobic work than during passive recovery. Recent work indicates that a combination of high- and low-intensity work may be optimal in reducing blood La. We tested this hypothesis by measuring the changes in blood La levels following maximal exercise during four different recovery patterns. Immediately following 50 S of maximal work, subjects (n = 7) performed one of the following recovery treatments for 40 min: 1) passive recovery (PR); 2) cycling at 35% maximal O2 uptake (VO2 max) (35% R); 3) cycling at 65% VO2 max (65% R); 4) cycling at 65% for 7 min followed by cycling at 35% for 33 min (CR). The treatment order was counterbalanced with each subject performing all treatments. Serial blood samples were obtained throughout recovery treatments and analyzed for La. The rate of blood La disappearance was significantly greater (P less than 0.05) in both the 35% R and CR when compared with either the 65% R or PR. No significant difference (P greater than 0.05) existed in the rate of blood La disappearance between the 35% R and CR. These data do not support the hypothesis that exercise recovery at a combination of intensities is superior to a recovery involving continuous submaximal exercise in lowering blood La following maximal work.     

Oral contraceptive cycle phase does not affect 200-m swim time trial performance

The purpose of this study was to examine whether swimming performance was affected by acute hormonal fluctuation within a monophasic oral contraceptive (OC) cycle. Six competitive swimmers and water polo players completed a 200-m time trial at 3 time points of a single OC cycle: during the consumption phase (CONS), early (WITH1), and late in the withdrawal phase (WITH2). Split times and stroke rate were recorded during the time trial, and heart rate, blood lactate, glucose, and pH were measured after each performance test. Resting endogenous serum estradiol and progesterone concentrations were also assessed. No significant differences were observed between phases for body composition, 200-m swim time, mean stroke rate, peak heart rate, or blood glucose (p > 0.05). The mean peak blood lactate was significantly lower during WITH2 (9.9 ± 3.0 mmol·L(-1)) compared with that of CONS (12.5 ± 3.0 mmol·L(-1)) and mean pH higher during WITH2 (7.183 ± 0.111) compared with that of CONS (7.144 ± 0.092). Serum estradiol levels were significantly greater during WITH2 compared with that during WITH1 and CONS, but there was no difference in serum progesterone levels. These results demonstrate that for monophasic OC users, cycle phase does not impact the 200-m swimming performance. There was a reduction in blood lactate and an increase in pH during the withdrawal phase, possibly because of an increase in fluid retention, plasma volume, and cellular alkalosis. Therefore, female 200-m swimmers taking a monophasic OC need not be concerned by the phase of their cycle with regard to competition and optimizing performance. However, coaches and scientists should exercise caution when interpreting blood lactate results obtained from swimming tests and consider controlling for cycle phase for athletes taking an OC.     

Effect of postactivation potentiation on swimming starts in international sprint swimmers

The aim of this study was to investigate the effects of postactivation potentiation (PAP) on swim start performance (time to 15 m) in a group of international sprint swimmers. Nine international sprint swimmers (7 men and 2 women) volunteered and gave informed consent for this study, which was approved by the university ethics committee. Initially, swimmers performed a countermovement jump (CMJ) on a portable force platform (FP) at baseline and at the following time points ～15 seconds, 4, 8, 12, and 16 minutes after a PAP stimulus (1 set of 3 repetitions at 87% 1 repetition maximum [RM]) to individually determine the recovery time required to observe enhanced muscle performance. On 2 additional days, swimmers performed a swim start to 15 m under 50-m freestyle race conditions, which was preceded by either their individualized race specific warm-up or a PAP stimulus (1 set of 3 repetitions at 87% 1RM). Both trials were recorded on 2 cameras operating at 50 Hz with camera 1 located at the start and camera 2 at the 15-m mark. Peak vertical force (PVF) and peak horizontal force (PHF) were measured during all swim starts from a portable FP placed on top of the swim block. A repeated measures analysis of variance revealed a significant time effect with regard to power output (PO) (F = 20.963, p < 0.01) and jump height (JH) (F = 14.634, p < 0.01) with a paired comparison indicating a significant increase in PO and JH after 8 minutes of recovery from the PAP stimulus. There was a significant increase in both PHF and PVF after the PAP stimulus compared to the swim-specific warm-up during the swim start (PHF 770 ± 228 vs. 814 ± 263 N, p = 0.018; PVF: 1,462 ± 280 vs. 1,518 ± 311 N, p = 0.038); however, time to 15 m was the same when both starts were compared (7.1 ± 0.8 vs. 7.1 ± 0.8 seconds, p = 0.447). The results from this study indicate that muscle performance during a CMJ is enhanced after a PAP stimulus providing adequate recovery (～8 minutes) is given between the 2 activities. In addition, this study demonstrated that swimmers performed equally well in terms of time to 15 m when a PAP stimulus was compared to their individualized race specific warm-up and indicates that PAP may be a useful addition to a warm-up protocol before races. However, more research is required to fully understand the role PAP plays in swim performance.