Introduction
Competitive swimming is an intense and demanding sport that requires long hours of repetitive movement patterns, sometimes performed twice a day over the course of the season. At the high school and collegiate levels, swim coaches prepare their athletes to achieve peak swim fitness just before the end-of-season competitions to optimize performance. In turn, it is common for these athletes to intentionally take 4–6 weeks off from training after the last major competition in an attempt to promote optimal physiological and psychological recovery and prevent overuse injuries (34 18
It is well documented that exercise training promotes positive adaptations to body composition (3,4 3,35 3,4,9,16,27 6 7 8 31 11,16,17 16,19 5,36 10,14 9 2 max, 54.9 ± 5.8 ml·kg− 1 ·min− 1 ) (1 2 peak, resting metabolic rate (RMR), mood state, and fasting lipid levels in collegiate level swimmers. We hypothesized that this period of swim DT, although necessary to help the body recover from the competitive swim season and prevent overuse injury, will result in increased body weight and BF and decreased V[Combining Dot Above]O2 peak and resting metabolism in these collegiate athletes. These deleterious changes may make it harder for these athletes to regain their fitness and negatively impact their long-term health. As such, it may be more advantageous to devise transition phase schedules that not only allow for sufficient rest, recovery, and overuse injury prevention, but this also maintains cardiovascular and metabolic health in these athletes.
Methods
Experimental Approach to the Problem
This study was designed to test the hypothesis that approximately 5 weeks (35–42 days) of swim DT (Independent variable) would result in significant decrements to body composition, aerobic fitness, RMR, and fasting blood lipids (dependent variables) in collegiate swimmers. Measurements during this study were conducted during 2 distinct phases: (a) during a habitually trained (TR) state approximately 48 hours after a typical exercise bout (during the week before end-of-season championships, mid-February) and (b) after 35–42 days of DT (just over a month after the season ended, mid-March). The participants were instructed to engage in no-swim training but instead engage in other forms of physical exercise such as light-moderate physical activity (<6.0 METS) and normal activities of daily living for the entirety of the DT period. Some of the activities that the participants engaged in during the DT period included running, cycling, and weight training. In addition, all the participants were instructed to maintain a food and beverage intake pattern similar to that of their TR state to avoid any confounding influence of nutritional intake during the DT period. Compliance was verified via weekly phone, email, and personal contact over the 35- to 42-day DT phase by research personnel. All the measurements were made over 2 consecutive days (visit 1 and visit 2) during both the TR and the DT phases of the study. The subjects were instructed to fast for 12 hours before each test day but stay very well hydrated before arriving at the laboratory. During visit 1 of both the TR and the DT phases, total body mass (TBM), RMR, and body composition were measured between 0600 and 0800 hours. Fasting blood samples were also collected for analysis of glucose and lipid concentrations immediately after the RMR measurement. The participants were instructed to abstain from caffeine, alcohol, and exercise for 24 hours before TR and DT visit 1. The participants were then instructed to arrive back to the laboratory that same day for visit 2 of each phase, at which time V[Combining Dot Above]O2 peak was measured between 1500 and 1700 hours. All the participants were familiarized with all the testing procedures before their first TR visit 1. All the participants were asked to record all food and beverages for 2 days before TR visit 1 testing and then asked to consume the same food and beverages for 2 days before the DT visit 1 to remove the effects of varying nutrient and fluid intake on outcome variables.
Subjects
Eight healthy, Caucasian, Division III collegiate swimmers (4 female: age 19.5 ± 1.2 years, height 165 ± 1.6 cm, mass 64.2 ± 8.3 kg; 4 male: age 19.5 ± 1.0 years, height 174 ± 4.2, mass 73.5 ± 9.7 kg) participated in this study. All the participants were in excellent overall health; had no history of cardiovascular, metabolic, or hormonal disorders; and used no medications other than birth control, antidepressants, or occasional over-the-counter aspirin or ibuprofen. All the participants were members of the Skidmore College varsity swim team and had been training (>10 h·wk− 1 ) and competing for 5 months before study participation. All the participants had been involved in competitive swimming for a minimum of 5 years before this study and routinely engaged in high-intensity exercise including swimming and resistance exercise training for the past 7 months. Participant characteristics are given in Table 1 . Because of the similar response between male and female participants, the genders were averaged together (n = 8) for all the results reported in this study. This study was approved by Skidmore Colleges' human participants Institutional Review Board. All the participants were informed as to the experimental procedures and signed informed consent statements and medical history forms in adherence with the human subjects' guidelines of Skidmore College and with the current national and international laws and regulations governing the use of human subjects before any data collection.
Table 1: Participant characteristics.*†
Procedures
Body Mass and Height
The TBM was measured after an overnight fast and urine void on the morning of visit 1 testing in both the TR and DT states. The participants were clothed in shorts and tee shirt and weighed to the nearest ±0.1 kg on a calibrated balance beam scale. Height was assessed to the nearest 0.10 cm using a sliding vertical scale stadiometer. Waist, hip, thigh, and arm circumferences were also measured using a flexible measuring tape using standardized protocols (12
Resting Metabolic Rate
The participants were transported to the Human Performance Laboratory immediately upon waking in the morning by a research technician. Upon arrival, height and weight were recorded, and the participants were asked to lie down quietly in a supine position for 15 minutes before the testing began. After the rest period, RMR was measured between 0600 and 0730 AM for 30–45 minutes with a computerized open-circuit indirect calorimeter (VacuMed, Ventura, CA, USA). Briefly, the participants were positioned supine and fitted with a facemask (model 7900; Hans-Rudolph, Kansas City, MO, USA) connected to corrugated tubing that was in turn attached to the metabolic cart. A constant fraction of expired air was withdrawn, dried, and delivered to a zirconium-cell O2 analyzer (Ametek, Pittsburgh, PA, USA) and an infrared CO2 analyzer (Ametek). Energy expenditure (kilocalories per minute) was calculated from the equation of Weir (37 r ) for measurement of RMR in our laboratory is 0.90.
Body Composition
Total body composition was determined by dual energy x-ray absorptiometry (DXA; software version 4.1, model DPX; Lunar, Madison, WI, USA) with subjects in the supine position as previously described (3 r ) and coefficient of variation (CV) for whole-body composition analysis in our laboratory with n = 12 is r = 0.99, CV = 0.64%, and r = 0.98, CV = 2.2%, for fat-free mass (FFM) and FM, respectively.
Blood Lipids
Twelve-hour fasted blood samples were obtained via a finger stick and subsequently analyzed for total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), triglycerides (TRGs), and glucose (GLU) concentrations (milligrams per deciliter) using the Cholestech LDX blood analysis system (Hayward, CA, USA). Measured total blood cholesterol, HDL-C, and TRG values were used to calculate low-density lipoprotein cholesterol (LDL-C) (17 r ) and CV in our laboratory with n = 15 is r = 0.95, CV = 3.2%, r = 0.94, CV = 2.5%, and r = 0.97, CV = 5.3% for TC, GLU, and HDL-C (milligrams per deciliter), respectively.
Peak Oxygen Consumption and Time to Exhaustion
Peak oxygen consumption was determined by a progressive and continuous test to exhaustion on a cycle ergometer (Monark ergometer model 864) in a well-ventilated facility at neutral room temperature (18–20° C). Seat height was adjusted to an optimal height (∼15° bend in the knee with leg in the maximal downstroke of the pedal). The same seat height was used for testing V[Combining Dot Above]O2 peak in the both the TR and DT states. The initial work rate for each subject was set to 50 W for the first 3 minutes and was increased 25 W every 2 minutes until volitional exhaustion or until the participants were unable to maintain 60 rpm. Expired gases were collected throughout the test, and O2 and CO2 levels were determined on electrochemical O2 (Ametek) and infrared CO2 analyzers (Ametek), respectively. The V[Combining Dot Above]O2 peak was defined as the highest value obtained (60-second average). Heart rate was recorded during testing using a Polar heart rate chest strap and watch (Polar, Port Washington, NY, USA). Perceived exertion was measured using the Borg perceived exertion scale. The total time to exhaustion (TTE) during the V[Combining Dot Above]O2 peak test was also recorded in both the TR and DT states.
Mood State
The profile of mood states (POMS) questionnaire (23 2
Statistical Analyses
Data were analyzed using IBM SPSS version 19.0 software (Chicago, IL, USA). All outcome variables were analyzed using a paired t -test to compare TR and DT values. All data are expressed as mean ± SD , unless noted otherwise. Statistical significance was determined at p ≤ 0.05.
Results
Body Weight and Composition
Body weight increased significantly after 35–42 days of swim DT (Table 2 ; Figure 1 ). This was entirely because of a 12% increase in body FM and percent (p < 0.001), as lean mass was unchanged (p = 0.99). In fact, in all 8 subjects, there was an increase in BF (Figure 2 ). Waist circumference was significantly increased (p = 0.03; Table 2 ) though there were no changes in hip, thigh, or arm circumferences (data not shown).
Table 2: Body weight and composition in the TR state and after approximately 5 weeks of swim DT.*†
Figure 1: Individual changes in body weight (BW) in the trained (TR) state and after approximately 5 weeks of swim detraining (DT).
Figure 2: Individual changes in percent body fat (BF) in the trained (TR) state and after approximately 5 weeks of swim detraining (DT).
Peak Oxygen Consumption
There was a significant 7.7% decrease in V[Combining Dot Above]O2 peak during the 35- to 42-day DT period (p = 0.02; Table 3 ; Figure 3 ). Maximum heart rate (p = 0.27), respiratory quotient (p = 0.8), and perceived exertion (p = 0.79) did not differ between TR and DT. Time to exhaustion was significantly lower in DT than in TR (p = 0.04; Table 3 ; Figure 4 ).
Table 3: Peak exercise testing in the TR state and after approximately 5 weeks of swim DT.*†
Figure 3: Individual changes in peak oxygen consumption (V[Combining Dot Above]O2 peak) in the trained (TR) state and after approximately 5 weeks of swim detraining (DT).
Figure 4: Individual changes in time to exhaustion (TTE) in the trained (TR) state and after approximately 5 weeks of swim detraining (DT).
Resting Metabolic Rate
The RMR was significantly lower (7%) in the DT compared with that in the TR state (p = 0.008; Figure 5 ).
Figure 5: Resting metabolic rate when trained and after approximately 5 weeks of swim detraining. Values are mean ± SD . *Significantly different from trained bar, p < 0.05.
Blood Lipids
Total cholesterol, HDL-C, and LDL-C remained unchanged, and TRGs showed a trend to increase after DT (p = 0.06; Table 4 ).
Table 4: Blood lipids in the TR state and after approximately 5 weeks of swim DT.*†
Mood State
Psychological mood state remained unchanged after the 5 weeks of DT (Table 5 ).
Table 5: Profile of mood states in the TR state and after approximately 5 weeks of swim DT.*†
Discussion
The primary goal of the current investigation was to examine the effects of 35–42 days of DT, after a competitive swim season, on body composition, resting metabolism, plasma lipid concentrations, peak oxygen uptake (V[Combining Dot Above]O2 peak), and psychological mood state in collegiate swimmers. The main findings of this study were that 35–42 days of swim DT involving light-moderate physical exercise after a competitive swim season in healthy college-aged men and women resulted in a significant (a) 1.3% increase in body weight; (b) 12.2% increase in BF; (c) 7.7% decrease in peak oxygen consumption; (d) 7% decrease in RMR despite preservation of lean mass; and (e) no change in blood lipids or mood state. The implications from these findings strongly suggest that competitive collegiate swimmers and their coaches should devise transition, off-season periodization training programs that provide adequate rest and recovery from the demanding competitive season but that also allow these athletes to maintain healthy body composition and cardiovascular fitness during this time. Undoubtedly, competitive swimmers need time off after their season to recover and prevent overuse injuries. However, it is equally important that significant DT does not ensue during this off-season period that negatively impacts cardiovascular, metabolic and body composition health, making subsequent performance gains more difficult. Our findings stress the importance of devising specific transition phase training practices that enhance physiopsychological recovery after the intense swim season but that also provide opportunities to maintain overall health and well-being and promote future performance gains.
In only 35–42 days of nonstructured exercise training after a competitive swim season, the average body weight of our swimmers increased from 68.9 ± 9.7 to 69.8 ± 9.8 kg. This was entirely because of a gain in the FM as evidenced by a 2% increase (TR, 22.3 ± 11.5 vs. DT, 24.3 ± 11.0, p < 0.001) in %BF (Table 1 ). To the authors' knowledge, there has only been one other study that followed swimmers after a competitive season and measured changes in body composition. Almeras et al. (1 −1 , an amount the authors hypothesized was largely attributable to the swimmers' previous energy cost of training. Our swimmers gained 0.9 kg over 5 weeks, averaging approximately 0.18-kg fat gain per week. This difference is likely because of the length of the in-season training period (13 vs. 5 months) and fitness levels of the swimmers. Almeras et al (1 − 1 and a V[Combining Dot Above]O2 max of 54.9 ± 5.8 ml·kg− 1 ·min− 1 , whereas swimmers in this study trained approximately 10 h·wk− 1 and had a V[Combining Dot Above]O2 peak of 46.7 ± 10.8 ml·kg− 1 ·min− 1 . Our results are also in agreement with those of previous work from our laboratory and others documenting significant increases in BF and other deleterious health outcomes after DT from endurance sports (5,16,28,36 2 13 21 13,21
The rapidity and magnitude of fat gain after cessation of exercise suggests that athletes do not spontaneously reduce caloric intake in response to reduced training. Studies in which short-term energy expenditure is manipulated support this observation. In a recent study in which participants resided for 7 days in a whole-body indirect calorimeter, Stubbs et al. reported that the imposition of sedentary behavior (compared with moderate exercise) does not cause a compensatory decrease in ad libitum energy intake (32 24
Because our measurements of body composition were only taken at baseline and follow-up, it is impossible for us to determine if FM steadily increased over the 6-week DT period or, if after an initial period of excess caloric intake, energy intake was reduced to levels similar to energy expenditure. Despite the consistent response among the participants studied in the short term to overeat during periods of reduced physical activity (24,32 − 1 (22,30,33
Body circumference measurements suggest that the fat accumulation during DT in our swimmers was predominantly in the abdominal region. Circumference measures of the arms, hips, and thighs were unchanged after DT (p = 0.63, 0.37, 0.13, respectively). In contrast, there was a significant increase in waist circumference (p = 0.029; Table 2 ). Because our swimmers were young and healthy and well within the healthy range of waist-hip ratios, even after DT, this slight increase in waist circumference may not have immediate health ramifications. However, given the association between abdominal fat accumulation and a variety of morbidities (29
From an exercise performance standpoint, it is quite logical that 35–42 days of DT would result in a decrement in performance capabilities. Indeed, from our data, we conclude that peak oxygen consumption (−7.7%) and TTE on a cycle ergometer (−9.0%) were significantly reduced after DT. These results agree with those of García-Pallarés et al. who reported a significant 11.3% reduction in maximal aerobic power (15 2 max) and a significant 3.3% decrease in paddling speed at V[Combining Dot Above]O2 max (14 2 peak is consistent in the literature after a cessation of exercise training for 3–12 weeks (10,14,16,28,35 35 2 peak. This type of training will significantly reduce training volume to help aid in recovery and prevent overuse injury during the off-season transition phase.
Blood concentrations of TC, TRGs, HDL, and LDL in this study were unaffected by 35–42 days of DT. Alternatively, Giada et al. reported significant increases in TRGs, very low–density lipoproteins, and the LDL/HDL ratio with concurrent decreases in HDL cholesterol in both older and younger adult male cyclists after 8 weeks DT (16 28
Mood state was not affected by 35–42 days of DT (Table 5 ). This result was surprising because an increase in the volume of swim training (26 25 20
In summary, 5 weeks of swim DT after a competitive swim season in healthy young collegiate athletes significantly increases body weight, BF, and waist circumference and decreases aerobic fitness and resting metabolism. Although an off-season is a useful and often beneficial time period for athletes to rejuvenate and recover from a strenuous season, many may experience deleterious physiological changes that may affect swim performance and overall health in the long term. Thus, it is important that coaches and athletes are cognizant of these pitfalls and incorporate nutritional and exercise training practices that are effective at maintaining cardiovascular, metabolic, and body composition health during the transition phase of the periodization schedule.
Practical Applications
Detraining for 35–42 days after a competitive swim season is not recommended for athletes. Athletes and coaches need to be aware of the rapid onset of negative consequences to DT and plan off-season training and nutritional practices accordingly so as not to suffer health and performance decrements. It seems logical to incorporate an appropriate off-season rest period and “active” rest periodization. However, specific guidelines regarding exercise frequency, intensity, and duration along with healthy nutritional strategies need to be followed by these athletes to maximize recovery, prevent overuse injuries, and maintain cardiovascular fitness and metabolic and body composition health during the transition period. These strategies may include performing low-volume/impact, high-intensity interval training 1–2× per week and frequent consumption of protein-rich, nutrient-dense foods, which have been shown to enhance cardiovascular fitness and body composition and metabolic health.
Acknowledgments
The authors would like to thank the members of the Skidmore College men's and women's varsity swim team for their dedication to the DT protocol. The authors are also grateful to Sara Sloper and Karissa Ercolani for their hard work with the subject recruitment, testing, and data analysis. The results of this study do not constitute endorsement by the authors or the National Strength and Conditioning Association.
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