EFFECTS OF DRY-LAND VS. RESISTED- AND ASSISTED-SPRINT ... · Effects of dry-land vs. resisted- and assisted-sprint exercises on swimming sprint performances. J. ... The assisted sprint

Journal of Strength and Conditioning Research, 2007, 21(2), 599-605C) 2007 National Strength & Conditioning Association

EFFECTS OF DRY-LAND VS. RESISTED- ANDASSISTED-SPRINT EXERCISES ON SWIMMINGSPRINT PERFORMANCES

SEBASTIEN GIROLD,' DIDIER MAURIN,^ BENOIT DUGUE,2 JEAN-CLAUDE CHATARD,I ANDGREGOIRE MILLET^

'Laboratory of Physiology, PPEH, Faculty of Medicine Jean Monnet, Saint-Etienne, France; '^Laboratory ofExercise-Induced Physiological Adaptations (EA 3813), University of Poitiers, Poitiers, France; faculty of SportSciences, University Montpellier 1, Montpellier, France.

ABSTRACT. Girold, S., D. Maurin, B. Dugue, J.-C. Chatard, andG. Millet. Effects of dry-land vs. resisted- and assisted-sprintexercises on swimming sprint performances. J. Strength Cond.Res. 21(2):599-605. 2007.—This study was undertaken to com-pare the effects of dry-land strength training with a combinedin-water resisted- and assisted-sprint program in swimmer ath-letes. Twenty-one swimmers from regional to national level par-ticipated in this study. They were randomly assigned to 3groups: the strength (Sl group that was involved in a dry-landstrength training program where barhells were used, the resist-ed- and assisted-sprint (RAS) group that got involved in a spe-cific water training program where elastic tubes were used togenerate resistance and assistance while swimming, and thecontrol (C) group which was involved in an aerobic cycling pro-gram. During 12 weeks, the athletes performed 6 training ses-sions per week on separate days. All of them combined the sameaerobic dominant work for their basic training in swimming andrunning witb their specific training. Athletes were evaluated 3times: before the training program started, after 6 weeks oftraining, and at the end of the training program. The outcomevalues were the strength of the elbow flexors and extensors eval-uated using an isokinetic dynamometer, and the speed, strokerate, stroke length, and stroke depth observed during a 50-metersprint. No changes were observed after 6 weeks of training. Atthe end of the training period, we observed significant increasesin swimming velocity, and strengtb of elbow flexors and exten-sors both in the S and RAS groups. However, stroke depth de-creased both in the S and RAS groups. Stroke rate increased inthe RAS but not in the S group. However, no significant differ-ences in the swimming performances between the S and RASgroups were observed. No significant changes occurred in C. Al-together, programs combining swimming with dry-land strengthor with in-water resisted- and assisted-sprint exercises led to asimilar gain in sprint performance and are more efficient thantraditional swimming training methods alone.

KEY WORDS, weigbt training, stroke technique, muscularstrengtb

INTRODUCTION

everal conditioning training methods in swim-ming have been described to increase swim-mers' physical abilities (18, 25). The efficien-cies of the programs depend on the specificityof the event (5, 14, 23) and the intensity of the

training sessions (2, 4, 17, 24). Two main strategies havebeen developed in training methods for swimmers: in-wa-ter and dry-land methods.

Maglischo et al. (13) have analyzed the effects of re-sisted- and assisted-sprint sessions on a swimmer's tech-nique. Resisted sprint has been defined as an exerciserealized against a resistance added to the natural resis-tance of the water. The swimmer was tethered with an

elastic which increased the resistance during the swim.The assisted sprint corresponded to an exercise where theover-maximal speed was reached. The swimmer waspulled by an elastic during the swim. It has been shownthat assisted sprint induced an increase in stroke ratewithout any decrease in stroke length, whereas resistedsprint led to a decrease in both stroke rate and strokelength. The authors suggested that the assisted-sprintmethod was more efficient than the resisted-sprint meth-od for increasing swimmers' performances. Toussaint andVervoorn (27) have also reported that resisted-sprinttraining for 10 weeks induced a significant increase inperformance over 50, 100, and 200 meters by 2.0, 3.2, and1.8%, respectively.

The positive effects of dry-land upper limbs strengthtraining on sprint performances have also been reportedextensively, and generally the gains in sprint perfor-mance are consistent: between 1.3 and 4.4% (5, 18, 24).For example, Strass (24) showed that press and draw ex-ercises with barbells for 6 weeks led to a significant 4.4and 2.1% increase in performance over 25 and 50 m, re-spectively. Several studies have demonstrated a strongrelationship between upper body strength and sprintswimming performances over 25 yd and 50 m (10, 20, 22).However, 1 study (25) reported the absence of gain inperformance after a dry-land strength training period.Nevertheless, the dry-land strength training programused in this study was a strength endurance training pro-gram (8 to 12 repetitions of each exercise), which isthought unlikely to improve swimming sprint. Tanakaand Swensen (26) questioned the specificity of the resis-tance training methods in swimmers and stated that com-bined swim and traditional dry-land resistance trainingdid not enhance swimming performance, whereas com-bined swim and swim-specific in-water resistance train-ing increased swimming velocity. These data suggestedthat specific in-water resistance training would be moreefficient than dry-land training in swimmers. Surprising-ly, although the efficiency of dry-land and resisted- andassisted-sprint (RAS) training methods on sprint perfor-mance are both widely documented, to our knowledge, norandomized comparative studies have been performed sofar.

Therefore, the main purpose of our study was to com-pare the effects of combined dry-land strength with aswimming program with those of a combined RAS withthe same swimming program. Due to the greater speci-ficity of the in-water RAS method, this study tested thehypothesis that RAS induced some adaptations, leading

599

600 GiROLD, MAURIN, DUGU:^ ET AL.

TABLE 1. Main characteristics and weekly training volume of the 3 groups,'*

Strength groupAT = 7

Resisted- andassisted-sprint group

N =1Control group

N - 7Age (y)Height (m)Weight (kg)Arm span (mlSwimming (h)Dry-land training {h}Resisted- and assisted-sprint training (h)Running (h)Cycling (h)Training volume (h)

16.5 (2.5)1.71 (0.09)

64(8)1.78 (0.1)

7.51.5NA0.75NA9.75

16.5 (2.5)1.70 (0.11)

62(4)1.74(0.12)

7.5NA1.50.75NA9.75

16.5(1.5)1.71 (0.11)

62(4)1.75(0.11)

7.5NANA0.751.59.75

Values are mean (SD); significant at p < 0.05. No significant difference was found between the 3 groups. NA — not applicable.

to a greater short-term increase in sprint velocity inswimmers than dry-land strength training. Indeed, as re-ported by Tanaka and Swensen (26), Costill (5), and Stew-art and Hopkins (23), the improvement of swimming per-formance depends on the specificity of the training meth-ods. Nevertheless, in the present study, the dry-landstrength training program was defined as specific as pos-sible and was applied on specific muscle groups at a highintensity to improve sprint velocity.

METHODS

Experimental Approach to the ProblemThe main purpose of this study was to investigate howthe dry-land strength and resisted- and assisted-sprinttraining methods were able to enhance the performancesof swimmers in the 50-meter sprint. It was thus decidedto organize barbells and (specific) exercises such as pull-up in dry-land strength training conditions, and swim-ming exercises using specific elastics for resisted- and as-sisted-sprint training.

In dry-land strength training and in resisted- and as-sisted-sprint training, short and intensive sets were per-formed to increase maximal strength and anaerobic pow-er respectively, and thus to improve sprint abilities over50 meters dtiring a 12-week training period.

SubjectsA group of 21 competitive swimmers, from regional to na-tional level (10 men, 11 women) (mean ± SD, age: 16.5± 3.5 years, height: 170 ± 9 cm, weight: 62 ± 7 kg, armspan: 175 ±11 cm) took part in this study. The swimmersor their parents, if the swimmers were minors, signed aninformed consent form, and the subjects participated inthe study on a voluntary basis. This study was approvedby our University Committee on Human Research. Swim-mers trained an average of 5 x 1 hour 45 minutes perweek in the same swimming club and in the same con-ditions. All swimmers were sprinters from national to re-gional levels, which represent 87.7 ± 1.1% and 84.1 ±2.5% of world records over 100 and 200 m, respectively.They had a minimum of 5 to 6 years of practice.

ProceduresSwimmers were randomly divided into 3 groups: (a)strength (S), (b) RAS, and (c) control (C) groups. Eachgroup performed 6 training sessions per week for 12weeks. Each group had the same aerobic dominant workfor their basic training in swimming and running. The Sgroup was involved in a dry-land strength training pro-gram (see below). The RAS group was involved in a spe-

cific water strength training program (see below). Thecontrol group was involved in a 1.5-hour aerobic cyclingsession to counterbalance the 2 dry-land and resisted-and assisted-training sessions of 45 minutes per week,performed by S and RAS, respectively. Therefore, thetraining volume was exactly the same in all swimmers(Table 1).

No changes in the diet were requested. Swimmerswere asked to follow their usual eating habits.

The training program lasted from January to March,and represented the second macrocycle of the season. Ourathletes were preparing their national and regionalchampionships that were to take place in April. Duringthis macrocycle, there was no competition of importance,and the athletes' training program ended 2 weeks beforethe championships.

The strength training program for S concentrated onincreasing first the muscular strength of the upper limbs,second the abdominal muscles, and third the lower limbs.The upper limbs were principally the biceps and tricepsbrachii, the back, and the pectoral and the deltoid mus-cles. The lower limbs were principally the quadriceps,gluteus muscles, and calf. The strength training sessionswere 45 minutes long with a 10-minute warm-up using askipping rope. In each strength session the program wasthe same. There were 3 exercises per muscular groupwith a rest of 2 minutes between each exercise. This pro-gram was repeated 3 times in a row per session. A max-imum of 6 repetitions was realized in each exercise, ex-cept for the abdominal, for which 20 repetitions were re-alized. For the upper limbs, the exercises included press,pull-up, and draw with barbells. For the lower limbs, theexercises included different types of squat, and plyome-tric jumps. The load on the barbells was increased every3 weeks during the training period according to 1 repe-tition maximum (IRM). The intensity of the training var-ied between 80 and 90% of the maximal load. The subjectswere instructed to perform a concentric contraction asfast as possible, followed by a 3-second isometric contrac-tion and an eccentric resistance to return to the initialposition. The exercises rate was 1 movement every 6 sec-onds.

The RAS training program was performed with elasticbands. The swimmers were tethered to the starting plat-form. They wore a belt around the pelvis which was at-tached to a 5.6-meter elastic surgical tube (Paul Factory,Saint-Etienne, France; inside and outside diameters were8 and 12 cm, respectively). The other extremity of thetube was attached to the starting platform (Figure 1). Theelastic tube imposed a length (Y; in meters) strength (X;

DRY-LAND VS. SPEOHC TRAININC IN SWIMMING SPRINT 601

Swimmers movement

RESISTED-SPKINT

FIGURE 1. View ofthe swimmers' situations during the exer-cises in resisted and assisted sprint.

in Newtons) relationship on the swimmers expressed by:Y - 4.6403X + 3.1952. The training sessions lasted 45minutes with a standardized warm-up of 10 minutes. Ineach training session the program was the same. Therewere 2 sets of 3 repetitions per program, 1 set in frontcrawl and 1 set in speciality to make the training moreinteresting for the athletes, with 30 seconds of rest be-tween each repetition. This program was repeated 3 timesper session. Between each program, swimmers performed200 m of easy swimming as an active recovery. The se-quence of resisted and assisted sprint was realized in thefollowing manner (Figure 1): the swimmers first swam inresisted sprint, until they arrived either at the mechani-cal stretching limit ofthe elastic (about 25 meters), or totheir own limits, which meant swimming without movingforward. The return was performed in assisted sprint.The elastic tube pulled the swimmer toward the point ofarrival with an initial force of 60 N. During the swim, anassistant maintained the elastic as tight as possible tomaintain the same force throughout the sprint. Theswimmers were asked to follow the speed given by theelastic by having a high stroke rate and by trying to keeptheir stroke distance. The variation of the exercise inten-sity was induced by the increase of the distance reachedin resisted sprint, and/or by the speed reached in resistedand assisted sprint.

Running (for the 3 groups) and cycling (for C) trainingsessions were performed once a week, at a low intensity(between 60 and 70% of maximal heart rate), during 45-minute and 1-hour 30-minute sessions, respectively.

As previously mentioned, the swimming training pro-gram was the same for the 3 groups and consisted of 5sessions of 1 hour 45 minutes per week. These sessionsconsisted of a combination of dominant aerobic work oflong sets at a moderate intensity with a short recoverytime in front crawl with technical work in medley. Thetraining volume was 5,000 ± 500 m per session.

Swimming PerformancesSwimming performances were measured before the startofthe training program (WO), after 6 weeks (W6) of train-ing, and after 12 weeks (W12) of training. Measurementswere performed on the same day of the week and at thesame time ofthe day, during a 50-meter front crawl, div-ing start following a starter's instructions, at maximal

speed in a 25-m pool, about 15 minutes after a 2000-mstandardized warm-up. Swimmers performed their 50 mone by one, from the slowest to the fastest as it happenedin competition, at a rate of approximately 1 departureevery 35 to 40 seconds. Timing was manual.

Technical ParametersAll 50-m trials were video recorded with a digital camera(Sony miniDV) at a frequency of 25 Hz. The stroke rate,length, and depth were measured with picture digitizersoftware Pinnacle (Studio Pinnacle System, Inc, Moun-tain View, CA). A minimum of 3 complete stroke cycleswere analyzed during each 50 meters, over a distance of10 meters which corresponded to the field ofthe camera.The camera was placed 12.5 m from the edge ofthe pool,so the recording started 7.5 m after the departure until17.5 m of each 25 m. The camera was placed in a Plexiglaswaterproof box at a depth of 0.15 m. A ruler graduatedevery meter was placed in the field of the camera at adepth of 0.15 m in the swimmer's lane for calibration.

Muscle Strength MeasurementsThe flexion-extension peak torques (Nm) of the 2 fore-arms were measured with an isokinetic dynamometer(Cybex, Medimex Factory, Tassin la Demi Lune, France)at WO, W6, and W12. The forearm peak torque was re-tained because forearm forces account for a large part oftotal arm propulsion, as demonstrated by Shleihauf et al.(21). Before the measurements, a 5-minute standardizedwarm-up and familiarization period was performed withthe apparatus at several submaximal velocities (60"-s"',180°-s ') and in isometric condition. These difTerent an-gular velocities were chosen hecause they seemed to bethe most representative of a swimmer's movement speed(15, 16). The measurements took place at the end of eachweek, 24 hours after the last training session. Swimmerslay down and were strapped at the shoulders and pelvis.The arm was maintained parallel to the Cyhex's arm le-ver. The spindle of the motor was positioned in line withthe center of rotation of the elbow joint. Measures wereperformed on the right arm. The subjects were asked toperform 2 maximal efforts. The best performance was re-tained. A 30-second rest period separated each test. Inisometric action, the effort lasted 5 seconds with a 2-mi-nute rest period between repetitions; the elbow angle he-tween the arm and forearm was set at 90°. Intraclass cor-relation coefficients of the physical strength measure-ments, assessed in 18 swimmers using the coefficient ofvariation ofthe difference between 2 measurements, were2.7%.

Swimmers' weight, height, and arm span were mea-sured at WO, W6, and W12.

Statistical AnalysesMean and standard deviation were calculated for all var-iables. Two-way repeated measures analyses of variance(groups IS, RAS, and C] x measures IWO, W6, and W12|)were used to compare the main characteristics: perfor-mances, muscular strength, stroke rate, stroke length,and stroke depth, of the 3 groups, before training began,at mid-training, and after training ended. A Tukey-Kra-mer post hoc test was used to localize the differences.Pearson correlation coefficients were calculated betweenthe performance and the difTerent measured parameters.For the whole group, stepwise regressions were calculat-ed between the 50-meter front crawl velocity (indepen-dent variable) and the other variables (dependent vari-

602 GiROLD, MAURIN, DUGU* ET AL.

TABLE 2. Characteristics of the 3 groups before training.^

Strength groupN = 7

Resisted- andassisted-sprint

groupN =7

Control groupN = 7

50-m performances (s) 29.59 (2.88)Stroke length (ml 1-60 (0.11)Stroke rate (cycle min ') 48.9(4.9)Stroke depth (m) 0.86(0.05)Strength ofthe elbow extensors in isometric (Nm) 40 (19)Strength ofthe elbow flexors in isometric (Nm) 39 (13.0)Strength ofthe elbow extensors in concentric at 60°s ' (Nm) 34.7 (12.4)Strength ofthe elbow extensors in concentric at 60" s ' (Nm) 31.3 (8.5)Strength of the elbow extensors in concentric at 18O''-s '

(Nml 33.4(10.6)Strength ofthe elbow flexors in concentric at 180° s ' (Nm) 30.3 (7.4)

30.94(1.59)1.58 (0.08)48.2 (3.5)0.82 (0.05)35.4 (6.5)40.1 (13.6)29.1 (8.8)27.7 (7.9)

30.1 (5.8)24.8 (9.7)

* Values are mean (SD); significant at p < 0.05. No significant difference was found between the 3 groups.

31.35 (2.30)1.56 (0.09)47.8(3.7)0.85 (0.06)39.4(17.1)42.7(19.1)36.1 (19.7)29.3 (9.6)

30.4 (6.2)27.1 (10.1)

able) using the Stat View 512+ program (SAS InstituteInc, Cary, NC). In all the statistical analyses, the 0.05level of significance was adopted. The sample size calcu-lation regarding the 50-m test was performed. Using adifference between the groups of 1.01 second, a standarddeviation of 0.68 seconds, a beta value of 0.80, and analpha value of 0.05, six volunteers should be a sufficientnumber of subjects to detect a significant difference at theend of the training program, sbould this difference exist.

RESULTS

Before training (WO) there was no significant differencein performance, technical, muscular strength, or morpho-logic parameters between the 3 groups (Table 2).

Effect of Training on Swimming PerformanceThe effects of training on swimming performance are pre-sented in Figure 2. A significant improvement in perfor-mance (p < 0.05) at W12 was observed in S and RASwhen comparing results with those obtained at WO. Nochanges in performance were observed in group C. Thechanges in performance were significantly different be-tween S (2.8 ± 2.5%) or RAS (2.3 ± 1.3%), and C (0.9 ±1.2%; p < 0.05) but not between S and RAS. It is worthnoting this change in performance in S and RAS was sig-nificant only during the last 6 weeks of the training pe-riod (between W6 and W12).

FIGURE 2. Evolution ofthe performances over 50 m, over the12-week training period; p < 0.05 (mean ± SD}.

Effect of Training on Technical ParametersThe effects of training on technical parameters are pre-sented in Table 3. After 12 weeks of training, stroke depthwas significantly (p < 0.05) decreased during the 50 me-ters in S and RAS, but not in C. Stroke rate was signifi-cantly increased (p < 0.05) in RAS and C, but not in S.There was no significant difference in technical parame-ters variation, expressed in percentage of baseline, be-tween the 3 groups, over the 12-week training period.

Effects of Training on Muscle StrengthThe efTects of training on muscle strength are presentedin Table 4. Afler 12 weeks of training, muscle strengthwas significantly (p < 0.05) increased in isometric con-dition for the elbow flexors in S and RAS, but not in C.Muscle strength was significantly ip < 0.05) increased inconcentric condition for the elhow extensors at 60" s ' inS and RAS, but not in C; and for the elbow flexors at6O''-s ' in RAS, but not in S and C. Muscle strength wassignificantly (p < 0.05) increased in concentric conditionfor the elbow extensors at 180°-S"' for the 3 groups. It isof interest to observe that most ofthe changes in musclestrength in S were significant only during the last 6weeks of the training period (between W6 and W12).When compared to haseline, the increase in musclestrength after 12 weeks of training was different in iso-metric condition for the elbow extensors between S (45.5± 38.7%) and both RAS (12.4 ± 18.7%) and C (7.7 ±16.1%; p < 0.05), but not between RAS and C, and for theelbow flexors hetween S (39.5 ± 32.4'if) and C (10.8 ±21.5%; p < 0.05), but not between S and RAS.

Performance variations over the 12 weeks of training,expressed in percentage of baseline, were correlated withstroke depth ir = 0.94; p < 0.05) and stroke rate (r =0.74; p < 0.05) variations in RAS, but this relationshipdid not occur in S and C; and also with muscle strengthvariations of the elbow extensors in concentric conditionat 180°-s-' (r - 0.84; p < 0.05) in S, but not in RASandC.

None of the parameters was correlated with perfor-mance in C after 12 weeks of training.

Training Effect: Comparison Between Strength,Technical, and Morphological ParametersIn S, stepwise regression analysis between swimmingperformance and physical strength, technical, and mor-phologic parameters at W12 revealed that muscle

DRY-LAND VS. Srecinc TRAINING IN SWIMMING SI'RINT 603

strength gain in concentric condition for the elbow exten-sors at 180°-s ' (IS180E) was the most significant factor,while the arm span (AS) was the second most importantfactor. The effects of these 2 factors were additive; theefTect of AS significantly increased the coefficient of cor-relation between performance and IS180E from 0.84 to0.98 (p < 0.05), according to the equation:

Performance variation

= (0.078 X IS180E) + (-4.027 x AS) + 0.712

Similarly, in RAS, the decrease in stroke depth fSD) wasthe most sigjiificant factor, while the increase in strokerate (SR) was the second most important factor to explainsprint performance. The effects of these 2 factors wereadditive; the effect of SR significantly increased the co-efficient of correlation between performance and SD from0.94 to 0.98 (p < 0.05), according to the equation:

Performance variation

= (-1.128 X SD) + (-0.75 X SR) + 0.410

In C, none of the factors was significantly correlated withthe performance.

Gender EffectThere was a similar gender percentage in each group, andthere were no significant differences in training effectsbetween men and women in the 3 groups.

DISCUSSION

The main findings of the present study are:

1. The 2 methods combining swimming and dry-landstrength or swimming and RAS were more efficientthan the swimming program alone in increasing sprintperformance, whereas no differences were observedbetween S and RAS. Muscle strength increased in Sand RAS, whereas stroke rate increased only in RAS.

2. The muscle strength gain in concentric condition of theelbow extensors was a good predictor of the 50-m per-formance in S, while the stroke depth and the strokerate variations were good predictors of the 50-meterperformance in RAS.

After 12 weeks of training, no significant differenceswere observed between S and RAS on performance gainover 50 m (Figure 1). The 2.8% increase in 50-m perfor-mance in S is close to the 2.1% gain reported by Strass(24) over 50 m after a 6-week dry-land (strength) trainingperiod, and to the 3.6% gain reported by Sharp et al. (20)over 25 yd after an 8-week dry-land (swim bench) train-ing period. The 2.3%^ increase in 50-m performance inRAS corroborated the results obtained by Delecluse et al.(6, 7) in athletics with similar methods, and the hypoth-esis of Maglischo et al. (13) on the efficiency of resistedand assisted training methods in swimming. Indeed, asthey measured their impact on technical parameters,Maglischo et al. (13) speculated that these training meth-ods would induce an increase in swimming performance.The S and RAS training methods were more efficient toincrease sprint performance than swimming programalone. These results are in agreement with the study ofTanaka et al. (26), indicating that combining swim andin-Iand or in-water swim-specific resistance training wasmore effective than swim-alone training in improvingswim performance. However, dry-land weight trainingdoes not seem to be the only way to overload functionalmuscles, and even if good results are obtained, the use of

a sport-specific program may also be of importance. Nev-ertheless, further investigations are required to deter-mine this aspect more precisely.

The strength group was more efficient than RAS toincrease the muscle strength (Table 4). Iln S, the 45%'increase in the isometric strength of elbow extensors isclose to the 20 to 40% gain reported by Strass (24) and tothe 20 to 75%. gain reported by Faigenbaum (8) after 12weeks of training. In RAS, the 32% increase in the con-centric strength of elbow extensors at 60° s ' is in agree-ment with the results reported by Delecluse et al. (6, 7)in athletics, indicating that resisted- and assisted-sprinttraining enhance strength and power (strength x speed).In the 2 groups, the greatest gain in muscle strength con-cerned the elbow extensors, i.e., the triceps brachii. Birrer(3) has previously shown the importance of the triceps inthe pushing phase for all strokes. Rouard et al. (19), andSchleihauf et al. (21) have also reported that peak forceoccurs at the end of the aquatic phase of the stroke duringforearm extension.

The strength training program realized by the S al-ternated dynamic phases in concentric conditions but alsophases in isometric and eccentric conditions, developing,therefore, first the gain in muscle strength at low velocity.This could explain why the most significant strength gainin S was measured in isometric condition. Delecluse et al.(7) suggested that a high-resistance and a high-velocitysprint training enhances power and movement speed dueto adaptive changes in the nervous system: high-resis-tance sprint first develops motor unit recruitment leadingto a gain in movement velocity that may be limited by thetime required for the motor units maximai recruitmentto generate maximal strength. In complement, high-ve-locity sprint develops movement speed (in spite of themovement length), combined with a gain in power at highvelocity. This could explain why the RAS group increasedthe concentric strength at 60° s ' and 180° s ' and in-creased the stroke rate. Resisted and assisted sprint rep-resents a dynamic strength training method, developingfirst the gain in muscle strength at high velocity.

Muscle strength and technical parameters were foundto be good predictors of 50-m swimming performance. Inthe present study, in S, the gain in 50-m performance wascorrelated to the gain in concentric strength of the elbowextensors at 180° s '. These data are in agreement withprevious studies (9, 10, 16, 20), showing a strong rela-tionship between the power of the upper limbs and thesprint swimming performance. In a 50-m sprint, strokerate is a key factor and is higher than those observed inother swimming distances. Thus, to be efficient, the 50-m swimmer has to generate a maximal strength at highstroke rate. This may be the reason why the strength gainat the highest angular velocity (180°-S"') was paramountin 50-m performance gain. These present data confirmedthe results of Costill (5) and Stewart and Hopkins (23)regarding the importance of the specificity of the trainingmethods, and those of Chatard and Mujika (4) and Mu-jika et al. (17) concerning the importance of the trainingintensity for improving swimming performance.

As reported by McCafferty and Horvath (14), the bodyadapts to adequately cope with the specific forms of ex-ercise stress applied, and the adaptive process does notinclude any capacity that extends beyond tbe specifictraining stress. In the present study, principally due tothe greater specificity of the in-water RAS method com-pared to in-land S, the hypothesis was that RAS shouldinduce adaptations leading to a greater short-term in-

604 GIROLD, MAURIN, DUGU^ ET AL.

TABLE 3. Evolution of technical parameters over the 12-week training period.''

Stroke rate (cycle-min') Stroke depth (m) Stroke length (ra)

WO W6 W12 WO W6 W12 WO W6 W12

S 48.9 (4.98)R A S 48.2 (3.5)C 47.8 (3.7)

49.8 (4.26)48.8 (3.8)1:47.8 (4.1)

50 7(3.71) 0,86(0.05) 0.84(0.04) 0.83 (0.05)§ 1.61(0.11) 1.60(0.10) 1.59(0.09)49.5 (3.4)§ 0.82 (0.06) 0.82 (0.051$ 0.80 (0.05)§ 1.58 (0.08) 1.57 (0.08) 1.56 (0.09)48.7 (3.7)§ 0.85 (0.06) 0.83 (0.07) 0.83 (0.07) 1.56 (0.09) 1.55 (0.08) 1.56 (0.08)

* Values are mean (S/»; significant at p < 0.05. WO = before training; W6 = after 6 weeks of training; W12 = after 12 weeks oftraining; S = strength group; RAS = resisted- and assisted-sprint group; C = control group.

t Significant difference between WO and W6.t Significant difference between W6 and W12.§ Significant difference between WO and W12.

crease in sprint velocity in swimmers. However, no dif-ferences were observed between S and RAS, which is notin agreement with the previous study of Tanaka et al. (26)indicating that combined swim and swim-specific (in-wa-ter) resistance training improves performance more thancombined swim and traditional (in-land) resistance train-ing. Tanaka et al. (26) speculated that the strength gaininduced by the dry-land program did not lead to increasedswim performance to the same extent as the in-water re-sistance program, mainly because the swimming strokeis highly technical. In the present study, dry-land train-ing was designed to be as specific as possible by the choiceof the muscular gi'oups and exercises (trajectory andspeed).

Two technical parameters, stroke depth and strokerate, were correlated to sprint performance, confirmingthe results of previous studies (1, 11, 12) on the impor-tance of the technical parameters. In RAS, the correlationbetween the gain in performance and the changes instroke depth and rate are in accordance with the obser-vations of Maglischo et al. (13). Those authors observeda significant increase in stroke rate during assistedsprint, and a significant decrease in stroke rate duringresisted sprint. They also observed that during assistedsprint swimmers tended to significantly decrease theirstroke length while during resisted sprint swimmerstended to maintain it. Maglischo et al. (13) also suggestedthat assisted sprint would be the most efficient methodto increase sprint performances, at the condition that af-ter RAS training the effects on the technique are main-tained without any assistance. In the present study, re-sisted- and assisted-sprint exercises were comhined. Aftertraining, an increase in stroke frequency (p < 0.05) witbno decrease in stroke length was observed. The combi-nation of the resisted and assisted sprints led to a new

technical adaptation. One may speculate, wben compar-ing the present results with those of Maglischo et al. (13),that the increase in stroke rate was influenced by theassisted sprint and that stroke length was conserved bythe resisted sprint. The gain in time during tbe stroke,that is necessary to increase the stroke rate witbout de-creasing the stroke length, was made possible by the de-crease in stroke depth. As the stroke rate increased forthe same stroke length, the swimmer's velocity was in-creased.

Both S and RAS groups significantly improved theirperformances with their specific training. However, wewere not ahle to distinguish any significant differences intheir swimming velocities at the end of the training pro-gram. The only significant difference concerned the gainin physical strength in isometric conditions at O^-s',which was more important in S. Nevertheless, isometricstrength gain at 0° s ^ was not related to performancegain and, therefore, does not seem to be an importantfactor in sprint performance. However, it has to he re-membered that both of our programs were specific con-cerning muscular groups, exercise trajectories andspeeds. Though the improvement may stem from differ-ent signaling pathways, none of the programs was ableto provide such a different stimulus that the outcomewould differ. However, a longer period of training mightlead to some different kinds of improvement. Further re-search is required to provide information on this aspect.

PRACTICAL APPLICATIONS

The present study shows that methods combining swim-ming and dry-land strength or swimming and resistedand assisted sprint were more efficient than the swim-ming program alone in increasing sprint performance in

TABLE 4. Strength variations in percentage of the baseline between the different measures.*

WO

wo

W6

to W12

to W6

to W12

SRASCSRASCSRASC

Isometric0"-s '

45.5 (38.7)t12.4(18.7)7.7 (16.1)

20.7 (26.4)t4.2 (20.3)2.9 (10.3)

20,6(20.8)119.4 117.4)11.7(17.6)

Extensors

Concentric60°-s-i

33.7 (27.6)t32.4 (21.1)i

7.9 (12.8)7.8(18.9)

10,2(21.2)13.9(19,9)25.4 (25.5)t22.5(25.1)t

1.1 (14.3)

180

35.228.915.7

7.56.29.5

27.224.2

6.3

"•s '

(31.9)1(18.8)t(10.6)t(21.4)(11.9)(12.5)(24.1)t(33.1)(10.5)

Isometric0"-s '

39.5 (32.4)117.6(13.8)t10.8 (21.5)13.2(13.1)3.6(17.6)4,6 (8.4)

23.4 (25.8)t15.9 (22.7)5.6 (20.7)

Flexors

Concentric60"s '

16.2 (10.4)10.1 (4.9)t7.8(16.1)2.1 (17.3)9.1 (7.7)t2.1 (4.9)

20.6 (23.4)1.2 (5.4)5.9 (13.3)

180

6.511.59.3

10.43.93.1

20.87.56.3

°-s-'(17.8)(18.2)(18.7)(19.7)(14.1)(14.9)(14.1)t(14.1)(13.1)

* Values are mean (SD). WO = before training; W6 = after 6 weeks of training; W12 = after 12 weeks of training; S = strengthgroup; RAS ^ resisted- and assisted-sprint group; C = control group.

t Significant at p < 0.05.

DRY-LAND VS. SPECIFIC TRAINING IN SWIMMING SPRINT 605

50-meter front crawl swimming. No differences were ob-served between dry-land strength training and in-waterresisted- and assisted-sprint training methods.

These training methods can be used during the entireseason. In a period of higb training volume, resisted andassisted sprint can develop strengtb endurance in the wa-ter, the bydrodynamic position, and the stroke rate. Inthis period it must be realized witb long sets at a mod-erate intensity with a short recovery time. In a period ofcompetition, resisted and assisted sprint can be used toincrease strengtb and power at a higb velocity, and tbestroke rate. In this period, it must be performed in sbortsets at maximal intensity with a long recovery time (atleast equivalent to tbe working time).

The corresponding time of the swimming velocity gainover 50 m after tbe 12-week training period was: 1.05 ±0.71 seconds in S, 0.96 ± 0.65 seconds in RAS, and 0.25± 0.69 seconds in C.

Gains in muscle strength were more important in Sthan in RAS. However, the RAS training led to an in-crease in stroke rate while sprinting. The gain in perfor-mance was mainly explained by a gain in concentricstrength and by an increase in stroke frequency. Furtherinvestigations are required to determine more preciselythe effect of resisted and assisted sprint on stroke pat-terns.

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AcknowledgmentsThe authors thank the swimmers for their voluntary participa-tion in the training program and Gilbert Lombai'd for his tech-nical assistance.

Address for correspondence to Dr. Sebastien Girold,[email protected].