Team handball is an Olympic sport now played IN-SEASON RESISTANCE TRAINING AND DETRAINING IN PROFESSIONAL TEAM HANDBALL PLAYERS INTRODUCTION METHODS

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1 Journal of Strength and Conditioning Research, 2006, 20(3), National Strength & Conditioning Association IN-SEASON RESISTANCE TRAINING AND DETRAINING IN PROFESSIONAL TEAM HANDBALL PLAYERS MÁRIO A. CARDOSO MARQUES 1 AND JUAN JOSÉ GONZÁLEZ-BADILLO 1,2 1 University Pablo de Olavide, Seville, Spain; 2 Spanish Olympic Committee, Madrid Studies, Spain. ABSTRACT. Marques, M.C., and J.J. González-Badillo. In-season resistance training and detraining in professional team handball players. J. Strength Cond. Res. 20(3): The object of this study was to investigate the changes in physical parameters produced during an in-season resistance training (RT) and detraining (DT, or RT cessation) in 16 high level team handball players (THPs). Apart from normal practice sessions, THPs underwent 12 weeks of RT. Subjects performed 3 sets of 3 6 reps with a load of 70 85% concentric 1 repetition maximum bench press (1RMBP), 3 sets of 3 6 reps with a load of 70 95% of 4 repetition maximum parallel squats (4RMPS), plus vertical jumps and sprints. The 1RMBP, 4RMPS, speed over 30 m (S30), jump (countermovement jump height [CMJ]; CMJ with additional weights [20kg and 40kg], and ball throw velocity (BTv) were tested before the experimental period (T1), after 6 weeks (T2), and after the 12-week experimental period (T3). Immediately after these 12 weeks, THPs started a 7-week DT period, maintained normal practices. The CMJ and the BTv were the only parameters evaluated during DT. The most important gains (p 0.001) in S30 were obtained between T1-T2 and T1-T3. The BTv improved significantly (p 0.001) only between T1-T2 and T1-T3. The most relevant increases (p 0.001) in jumping performance took place between T1-T2 and T1-T3. The 1RMBP showed significant increases (p 0.001) only between T1-T2 and T1-T3. The 4RMPS increased significantly between all testing trials. After the DT, THPs showed no significant losses in CMJ performance. However, they declined significantly in BTv (p 0.023). The results suggest that elite THPs can optimize important physical parameters over 12 weeks in-season and that 7 weeks of DT, although insufficient to produce significant decreases in CMJ, are sufficient to induce significant decreases in BTv. It is concluded that after RT cessation THPs reduced BTv performance. KEY WORDS. maximal dynamic strength, jumping, sprinting, ball throwing velocity INTRODUCTION Team handball is an Olympic sport now played professionally in Europe. However, despite increasing professionalization, there is a paucity of research data concerning performance. Two reasons for this may be suggested. Most of the investigation so far conducted has been published in eastern European countries and has not been readily accessible to the sport science community. Most coaches, moreover, have adopted conservative attitudes towards resistance training for team handball. Competitive team handball requires muscular strength, speed, and endurance. To date, it has not been very clear how these parameters change during the season in elite team handball players (THPs). Thus, only 2 studies (11, 14) have so far attempted to evaluate the effects of heavy resistance training (RT) programs on different physical parameters in competitive THPs. Research has focused more upon determining the influence of different speed-strength programs on throwing velocity (5, 16, 28, 29) or the relationship between throwing velocity and isokinetic strength (6, 9) rather than on jumping ability, sprint performance, or maximal dynamic strength. Also, there still exists limited information concerning training methods that increase the throwing ability in THPs (28). Here most of the research was carried out in other sports like baseball (20, 21, 23). Athletes often experience interruptions in training sessions and competition programs because of illness, injury, postseason break, or other factors, which may result in a reduction or cessation of their normal physical activity level (15, 18, 34). The magnitude of this reduction may depend upon the length of the detraining period (12, 13, 18, 34) in addition to training levels attained by the subject (15). Since, moreover, there exists only one previous study (28) investigating the effects of detraining (DT, or RT cessation) on THPs, the current investigation sought additional information on the effect of this upon jumping and throwing abilities. The hypothesis argued in this paper is that elite THPs can significantly increase the physical parameters of maximal dynamic strength, speed, jump, and throw performances in-season by combining normal technical and tactical sessions with an RT program over a consecutive 12-week period. Additionally, a 7-week DT period may produce significant decreases in physical performance, namely in jump and throw performances. Therefore, the object of this study was to investigate the changes in physical parameters produced during an in-season RT and DT in 16 high level THPs. The data so acquired may assist coaches in training athletes for an in-season RT program. METHODS Experimental Approach to the Problem In order to address the primary hypothesis presented herein, we selected 16 high level healthy THPs. Subjects were acquainted with all test procedures 2 weeks before the measurements were applied and fully warmed-up prior to testing. All testing was completed at the end of periodized RT and power training during the first part of the season to ensure that all athletes would be in a state of good overall performance. This entailed an RT program 1 2 times per week with medium to low intensity. The RT program included 2 maximal dynamic strength exercises (bench press and half squat) and 3 power exercises such as countermovement jump, medicine ball throwing, and sprinting. Consequently, all the athletes were at peak condition and were familiar with all the testing exercises, which they had been performing regularly as part of training. Apart from normal technical and tactical 563

2 564 MARQUES AND GONZÁLEZ-BADILLO TABLE 1. Parameter Selected characteristics of the subjects. Mean SD Age (y) Height (cm) Body mass (kg) Arm span (cm) Training (y) practice sessions (2 3 hours per day timed for 7:00 PM) and weekend competitions, all underwent 12 weeks of RT program divided into 2 cycles of 6 weeks. Upper- and lower-body maximal dynamic strength, speed, jump, and ball throw velocity (BTv) were tested at 3 intervals: before the experimental period (T1), after 6 weeks (T2), and after the 12-week experimental period (T3). Immediately following this, they commenced a 7-week DT period (T4), maintained alongside normal sessions. The inclusion of a control group in the study of top athletes is unethical. This is because the withholding of potentially important training would be detrimental for the development of the players so selected (17). To overcome this fact, the stability of the dependent variables was established with test-retest reliability measures (intraclass correlation coefficient [ICC]) or R (17). Subjects The sample comprised 16 high level male THPs (average age 23 years, range years; Table 1) including 4 international players. Two of the subjects had also participated in European senior championships. Participants were fully informed of all possible risks and stresses associated with the project and signed consent forms prior to participation. The study was conducted according to the Declaration of Helsinki and was approved by the Ethics Committee of the department responsible. Testing trials were performed in January and between February and June, respectively. All THPs has been trained by the same head coach and for the same club for the previous 2 years. Subjects were classified as experienced in RT programs. Training Protocol The RT program used consisted of 2 3 sessions per week over 12 weeks (2 cycles of 6-week periods) followed by DT lasting 7 weeks (Tables 2a and 2b). The RT program was directly supervised by present researchers, both of them specialists in RT, and by the team head coach. The principal RT exercises were, respectively, the bench press and parallel squat. Subjects performed 3 sets of 3 6 reps with a load of 70 85% concentric 1 repetition maximum bench press (1RMBP) and 3 sets of 3 6 reps with a load of 70 95% of 4 repetition maximum parallel squats (4RMPS). On completion, THPs then performed 2 explosive strength exercises: vertical jumps onto a box, followed by vertical jumps with additional weights (3 sets of 6 reps; loads varied between 20 and 30 kg, last 6 weeks only). The sprint exercise was consistently applied after warm up at the outset of each RT session (3 5 sets of m). In contrast, the other exercises were performed immediately after the team handball practices. Rest intervals of 2 minutes were permitted between sets and between categories. The RT was conducted on Monday and Wednesday (7:00 PM). Each RT session lasted for approximately 40 minutes including a prior warm up. During DT, RT was totally discontinued but the THPs maintained normal team handball practices and competitions. TABLE 2a. Resistance training programs between week 1 and week 6.* Exercises Session 1 Session 2 Session 3 Session 4 Session 5 Session 6 Parallel squat 70: : : : : : 3 6 CMJ onto a box Bench press 70: : : : : : 3 5 Sprints 3 20 m 3 20 m 4 20 m 4 20 m 4 30 m 4 30 m Exercises Session 7 Session 8 Session 9 Session 10 Session 11 Session 12 Parallel squat 80: : : : : : 3 4 CMJ onto a box Bench press 80: : : : : : 3 4 Sprints 5 30 m 5 20 m 5 30 m 5 20 m 5 30 m 5 20 m Exercises Session 13 Session 14 Session 15 Session 16 Parallel squat 95: : : : 3 4 CMJ onto a box Bench press 85: : : : 3 3 Sprints 5 30 m 5 20 m 5 30 m 5 20 m Principal exercises Training summary Sets reps Percent of MDE Parallel squat % Bench press % * CMJ countermovement jump; MDE maximal dynamic excercises. Rest intervals of 2 minutes were permitted between sets and between categories. Example: 70: 3 6: 3 sets of 6 reps with 70% of 4 repetition maximum parallel squats (4RMPS). Example: 70: 3 6: 3 sets of 6 reps with 70% of 1 repetition maximum bench press (1RMBP). The total number of repetitions lifted during the first training cycle in 1RMBP and 4RMPS exercises. The average percentage in MDE during the first training cycle (MDE 1RMBP and 4RMPS).

3 IN-SEASON RESISTANCE TRAINING 565 TABLE 2b. Resistance training programs between week 7 and week 12.* Exercises Session 1 Session 2 Session 3 Session 4 Session 5 Session 6 Parallel squat 70: : : : : : 3 6 CMJw 20 kg: kg: kg: kg: kg: kg: 3 5 CMJ into a box Bench press 70: : : : : : 3 5 Sprints 3 20 m 3 20 m 4 20 m 4 20 m 5 30 m 5 20 m Exercises Session 7 Session 8 Session 9 Session 10 Session 11 Session 12 Parallel squat 85: : : : : : 3 4 CMJw 35 kg: kg: kg: kg: kg: kg: 3 5 CMJ into a box Bench press 85: : : : : : 3 3 Sprints 5 20 m 5 30 m 5 30 m 5 20 m 5 30 m 5 20 m Principal exercises Training summary Sets reps Percent of MDE Parallel squat % Bench press % * CMJ countermovement jump; CMJw countermovement jump with additional weight; MDE maximal dynamic exercises. Rest intervals of 2 minutes were permitted between sets and between categories. Example: 70: 3 6: 3 sets of 6 reps with 70% of 4 repetition maximum parallel squats (4RMPS). Example: 70: 3 6: 3 sets of 6 reps with 70% of 1 repetition maximum bench press (1RMBP). The total number of repetitions lifted during the second training cycle in 1RMBP and 4RMPS exercises. The average percentage in MDE during the second training cycle (MDE 1RMBP and 4RMPS). Testing Procedures Briefly, subjects were acquainted with all test procedures 2 weeks before the measurements were applied and were fully warmed up prior to testing. All testing was completed at the end of a periodized strength and power training during the first part of the regular season (between October and December) to ensure that all athletes would be in a state of good overall performance. This entailed weight training 1 2 times per week at medium to low intensity levels and included 2 strength exercises (bench press exercise and a parallel squat); and another three power exercises such as countermovement jump, medicine ball throwing, and sprinting. Athletes were thus at peak condition and were familiar with the testing exercises, regularly performed as part of training. Sprint testing. Subjects were required to perform 3 maximum effort sprints of 30 m (S30). Times at 0 15 m (S15), m (S15 30) and S30 were recorded using Brower equipment (Wireless Sprint System, Fairlee, VT). Subjects performed trial sprints separated by 3 minutes of rest. Only the average of the best 2 sprints was considered. The S30 reported an ICC of 0.88 range (95% interval: ), and a CV (coefficient of variation) of 1.7%. Vertical jump height testing. The vertical jump height was measured by means of the CMJ test described by Bosco et al. (7). With a preparatory countermovement, each subject started from an erect standing position and the end of the concentric phase corresponded to a full leg extension: 180. The protocol required the performance of 3 jumps, each followed by 2 minutes of rest. An average of the 2 best jumps was taken. Subsequently, all performed trials of CMJ weighted with 20 and 40 kg (CMJ20kg and CMJ40kg) on a shoulder bar. The CMJ showed an ICC of 0.91 range (95% interval: ) and a CV of 4.7%. The CMJ with additional weights showed an ICC of 0.97 range (95% interval: ) and 0.87 range (95% interval: ) in CMJ20kg and CMJ40kg, respectively. These tests registered a CV of 2.2% and 5.4%, respectively, in CMJ20kg and in CMJ40kg. All tests were measured on a trigonometric carpet (Ergojump Digitime 1000; Digitest, Jyvaskyla, Finland). Throw testing. In order to assess the overarm throwing performance, a standard handball was used (mass 475 g; circumference 58 cm). Each subject then executed 5 trials of throws, performing a 3-step run, and then shooting the ball at maximum velocity to the middle of the goal (14). A 2-minute interval separated each trial. An average of the best 4 shots was taken. The throwing velocity was determined using a Speed Check Radar (Triad Industries Inc., Sault Ste. Marie, Ontario, Canada). This radar had a Doppler signal process to clock speeds. The internally located antenna, when activated, sends out radio signals at a specific frequency. The principal specifications are speed range k h 1 ; distance range (ball) approximately 9 m; accuracy ( 2/3 k h 1 ); frequency Hz; signal size approximately 60 vertical by 40 horizontal. The BTv showed an ICC of 0.96 range (95% interval: ) and a CV of 2.4%. Maximal dynamic strength testing. The maximal dynamic strength tests for the upper and lower muscles were carried out using 1RMBP and 4RMPS. In 1RMBP, the bar was positioned on the chest for a second. Thereafter, each subject was instructed to perform a concentric action from the starting position, maintaining the shoulders close to a 90 -abduction position to ensure consistency of shoulder and elbow joints throughout the movement. Each subject started with a weight of 30 kg, this being increased by increments of 10 kg until the player was unable to reach full arm extension. The last bearable load was determined as 1 repetition maximum (1RM). The rest time between the actions was 3 minutes. Only 2 subjects did not complete the 1RMBP because of shoulder injuries in previous practice incidents. They were, however, evaluated within 5 days of the initial tests, completing the full RT program. In the 4RMPS, the bar placed across the

4 566 MARQUES AND GONZÁLEZ-BADILLO TABLE 3. Mean ( SD) results of different parameters: ball throwing velocity (BTv: kilometers per hour), time in 30 m (S30m: seconds) and in respective time in the first 15 m (S15: seconds) and second 15 m (S15-30: seconds); before the experimental period (T1), after 6 weeks (T2), and after the 12-week experimental period (T3).* Tests (n 16) Significance (p value) Parameter: T1 T2 T3 T1 T2 T1 T3 T2 T3 BTv p p NS S p p p 0.05 S p 0.01 p NS S NS p p *NS no significant difference. trapezius at a self-chosen location and the starting position knee angle was set at 180 (full leg extension). The squat was performed to the parallel position, which when the grate trochanter of the femur was lowered to the same level as the knee. The correct position was monitored by both researchers. The subject then lifted the weight until his knees were extended. Each player started with identical weights of 70 kg, performing on command a series of 4 complete parallel squats. Subsequently, the weight was increased by 10-kg increments until the subject was unable to reach full leg extension. The last bearable load was determined as being 4RM. Five-minute rest intervals separated the 1RMBP and 4RMPS tests. The 1RMBP showed an ICC of 0.91 range (95% interval: ) and a CV of 9.7%. The 4RMPS reported an ICC of 0.95 range (95% interval: ) and a CV of 4.2%. Detrain testing. After 12 weeks of RT, THPs underwent a 7-week DT period, although keeping to scheduled team handball activities. Upon completion, all were measured on 2 dependent variables: CMJ and BTv. The protocols were identical to those previously described. Each subject was tested at weekly practice sessions in CMJ and BTv. These tests were applied every Thursday (at 7:00 PM) in order to assess the trajectory of jump and throwing performances. Training efficiency. To quantify the effort to benefit ratio, training efficiency was defined as the average percentage gain in bench press and squat performances during the 12-week training period divided by the total number of repetitions lifted at loads greater than 80% of 1RMBP and 4RMPS, respectively. Statistical Analyses Ordinary statistical methods were used for the calculation of average and standard deviations. A repeated-measures analysis of variance with Bonferroni adjustment was used to assess gains or losses. Measurement reliability was assessed in 2 trials separated by 5 days among 10 THPs. The Pearson correlation coefficient was calculated and the level accepted for statistical significance was p RESULTS The sprint and throw results are presented in Table 3. THPs experienced significant improvements in S30m across the whole range of measurements. The most important gains were obtained between T1-T2 (2.24%) and T1-T3 (3.13%). Similar results were achieved in S15m with significant performance gains between T1-T2 (1.57%) and T1-T3 (2.35%), except between T2-T3. Subjects also increased sprint performance in S15 30, between T1-T3 (3.66%) and T2-T3 (2.12%), except between T1-T2. Finally, THPs experienced increases in BTv but these were significant on only 2 occasions: T1-T2 (4%) and T1-T3 (6%). The results also showed significant gains in attained vertical jump height calculated in CMJ and in CMJ with additional weights during the course of the research (Table 4). The most important gains took place between T1- T3 (CMJ20kg: 20.8%) and in CMJ40kg (25.8%). However, the increase observed in CMJ was only 12.98%. The maximal dynamic strength results are presented in Table 5. After 6 weeks of RT, an increase of 1RMBP and 4RMPS was observed, corresponding to 16% and 30.7%, respectively. The 1RMBP increased significantly between T1-T3 and between T2-T3, corresponding to 27.7% and 10%, respectively. An increase in 4RMPS between T1-T3 and T2-T3 training periods was also observed, corresponding to 43% and 9.7%, respectively. After the 7-week DT period, THPs showed no statistically measurable losses in CMJ performance (Table 6 and Figure 1). However, they experienced significant decreases (Table 6 and Figure 2) in BTv (2.7%). The BTv and CMJ showed a high correlation (r 0.87; p 0.001) during the 12 weeks of weekly control training (Figure 3). During the experimental period (Table 7), average training efficiency in 1RMBP and 4RMPS was 0.14% lift 1 and 0.16% lift 1, respectively. No differences were observed in training efficiency between the first half (1 6 weeks) and the second half (7 12 weeks) of the training period. TABLE 4. Mean ( SD) results in centimeters of different parameters: countermovement jump height (CMJ), CMJ with different loads (CMJ20 kg and CMJ40 kg); before the experimental period (T1), after 6 weeks (T2), and after the 12-week experimental period (T3).* Tests (n 16) Significance (p value) Parameter: T1 T2 T3 T1 T2 T1 T3 T2 T3 CMJ p p p 0.05 CMJ20 kg p p p 0.05 CMJ40 kg p p p *NS no significant difference.

5 IN-SEASON RESISTANCE TRAINING 567 TABLE 5. Mean ( SD) results in kilograms of different parameters: concentric 1 repetition maximum bench press (1RMBP), 4 repetition maximum parallel squats (4RMPS) before the experimental period (T1), after 6 weeks (T2), and after the 12-week experimental period (T3). Tests* (n 16) Significance (p value) Parameter: T1 T2 T3 T1 T2 T1 T3 T2 T3 1RMBP p p p RMPS p p p 0.05 * In bench press exercise, n 14. TABLE 6. Mean ( SD) results in centimeters after 12 weeks the experimental period (T3) and after 7 weeks of detraining period (T4).* Tests (n 13) Variable: T3 T4 Significance (p value) T3 T4 CMJ NS BTv p 0.05 * CMJ countermovement jump; BTv ball throw velocity; NS no significant difference. Only n 13 because 3 players were injured in the last 7 weeks. FIGURE 3. Correlation between countermovement jump (CMJ) and ball throw velocity (BTv) during the weekly control training. The correlation results are outlined in Table 8. No correlation was found between 1RMBP and BTv during all testing trials. The correlations between CMJ and S30 and between CMJ and 4RMPS were not significant over T1- T2, T1-T3, and T2-T3. However, the present investigation showed significant correlations between S30 and 4RMPS between T1-T3 (r 0.52; p 0.04). In addition, significant correlations were also observed between CMJ and 4RMPS between T2-T3 (r 0.5; p 0.046). FIGURE 1. Time course effects of training and detraining on countermovement jump (CMJ). Values are mean ( SD). FIGURE 2. Time course effects of training and detraining on ball throw velocity (BTv). Values are mean ( SD). DISCUSSION Until recently, research has reported ambiguous results in the relations observed between maximal dynamic strength and sprint ability (19, 22, 32, 33). While some studies have claimed significant correlations between lower-body muscle strength measures and sprint performance (22), others have not (19). These conflicting results may be due to the fact that sprinting involves multiplejoint motions (30) with precise coordination between various muscle groups, which is not adequately assessed by single-joint tests that isolate muscles. Thus, the relative importance of various lower-body muscle groups to sprinting performance is not totally clear (19, 22, 30), especially when short and maximum-speed sprints are considered separately. Many sports comprise sets of variable skills and random motions, the performance of which require concentration upon a few basic and technical considerations (24). As a composite of such common skills, running demands some knowledge of its basic mechanics. According to Plisk (24), the reason that movements such as Olympic-style lifts, plyometrics, and medicine-ball drills are so effective

6 568 MARQUES AND GONZÁLEZ-BADILLO TABLE 7. Exercise Training efficiency.* AI per-exercise (%) 1st cycle 2nd cycle 1st cycle Total reps 2nd cycle 1st cycle ATE (% lift 1 ) 2nd cycle 1RMBP RMPS * 1RMBP 1 repetition maximum bench press; 4RMPS 4 repetition maximum parallel squat; AI average intensity; ATE average training efficiency. Total reps total number of repetitions (sets reps) lifted at loads greater than 80% of 1RMBP and 4RMPS, respectively. The average percentage gain in bench press and squat performances during the 12-week training period divided by the total number of repetitions lifted at loads greater than 80% of 1RMBP and 4RMPS, respectively. 1st cycle 1 6 weeks. 2nd cycle 7 12 weeks. TABLE 8. Correlations between strength vs. throwing velocity, power and throwing velocity, jumping and sprinting, jumping and strength, sprinting and strength; before the experimental period (T1), after 6 weeks (T2), and after the 12-week experimental period (T3). Tests (n 16) Variable: r T1 T2 p r T1 T3 p r T2 T3 1RMBP and BTv None None None CMJ and S NS 0.22 NS 0.1 NS CMJ and 4RMPS 0.18 NS 0.35 NS S30 and 4RMPS 0.24 NS NS * 1RMBP 1 repetition maximum bench press; CMJ countermovement jump; S30 speed over 30 m; 4RMPS 4 repetition maximum parallel squat; NS no significant difference. In bench press exercise only, n 14. in improving speed is that they cannot be performed without high power production, rapid force application, and acceleration. This is precisely why they correspond dynamically with so many athletic activities and deserve high priority in training. Moreover, inherently impulsive movements are not the only ways to develop speedstrength. Thus, brief maximal efforts and sub-maximal accelerative efforts are methods that can be applied to basic strength-training exercises (such as the squat) in order to complement reactive-ballistic actions. These methods improve an athlete s rate of force development and ability to accelerate heavy loads, including the athlete s own body mass (24). Despite the importance of the sprint technique for speed enhancement (24), this was not a component of normal day practices for the sample group of THPs. However, sprint, acceleration, and changes in direction are movements inherent in THPs daily practices and competitions. Recalling Plisk (24), these inherent factors may have aided athletes (THPs) in developing short sprint ability over the 12-week experimental period. Furthermore, the significant increments obtained in 4RMPS, and the strong correlations between S30 and 4RMPS (T1-T3; p 0.04), could also explain part of the improvements in sprint performance. Thus, the conjunction of all cited factors might well have been responsible for sprint performance increments during the 12 weeks of training. The effect of various RT programs on vertical jump ability has been researched extensively (1, 3, 12, 13, 31). Only Gorostiaga et al. (11), however, have investigated the influence of an RT program on THPs jumping performance. These authors reported significant increases in p vertical jump height in a nonstrength group (only team handball practice: 6%; p 0.001), while observing no significant changes in an RT and control groups in CMJ. In contrast, our study showed significant (12.98%; p 0.001) improvements in CMJ height during the T1-T3, suggesting that the addition of heavy RT programs did not interfere with jumping development at any rate in adults. Hakkinen and Komi (12), among others (1, 33), found similar results to those obtained in the present investigation (10.6%; p 0.001) but over 24 weeks. A special combination (13) of loaded squat jumps and specific plyometric jumps also resulted in significant improvements in CMJ height (17.5%; p 0.001). As in our research, these authors (13) also reported significant improvements in the CMJ40kg (26.2%; p 0.001). The degree of general strength gained through squat training does not seem to affect the degree of change in jumping performance. Alén et al. (2) claimed to observe no change in jumping performance in well-trained athletes following 24 weeks of heavy squat training, while noticing a large improvement in 1RM squat strength. Baker et al. (4) add that in trained athletes the relation between changes in 1RM squat performance and vertical jump consequent upon training was also nonsignificant (r 0.11). In contrast, the present investigation identified significant correlations (r 0.50; p 0.046) between CMJ and 4RMPS (only in T2-T3). Since the development of intermuscular coordination is basically a function of skill training (3), it can only be maximized by using loads that resemble the skill in terms of movement, speed, and pattern, so that technique is not altered drastically. A general exercise for the leg muscles (squat) using a heavy load is relatively more effective for development of intramuscular coordination, whereas the use of loaded-squat jumps is more effective for developing intermuscular coordination (3, 34). This could explain part of the improvements noticed in the present data. The probability of increasing the BTv by this means was certainly less than with the other variables, since throwing is a natural movement in team handball (5) and is perfected in elite players by constant practice and technique. However, subjects who participated in the present investigation significantly increased BTv between T1-T2 and T1-T3. During T2-T3, THPs continued progressing (1.8%) but not significantly. We suggest that in the last 6 weeks of RT, players might well have reached their BTv ceiling. With similar results, Hoff and Almasbakk (14) observed significant improvements in BTv after 9 weeks of heavy RT (17%; p 0.05). On the other hand, a 6-week period of heavy RT also produced a significant increase

7 IN-SEASON RESISTANCE TRAINING 569 (3.1%; p 0.001) in an RT group (combined RT with team handball practices) but no such increase in a control group nor in a further group who trained only in specific team handball skills (11). After 9 weeks of speed-strength programs, Barata (5) observed an increase in velocity of 11.5% when subjects trained with heavier balls. The control group, which had only normal team handball throwing practice, also showed a significant increase in BTv (7.8%; p 0.001). Van Muijen (29) also found a significant increase (2%; p 0.001) in this variable among competitive females when training with light medicine balls. Finally, Skoufas et al. (28) showed that training with 20% lighter handballs caused better ball release velocity (4.3%; p 0.05) than using normal balls. These findings could confirm the principle of training specificity, though some are difficult to interpret because of the subject s age or lack of throwing experience, and subjection to different RT programs (5, 11, 14, 16, 28, 29). A logical comparison between the present research and the studies attempted in baseball is suggested by the similarity of the throwing movement. Lachowetz et al. (20) reported an increase in BTv after an RT program (2.4%). After 10 weeks of RT, McEvoy and Newton (21) observed significant increments in throwing speed by 2.0% (p 0.05) in an experimental group (ballistic RT), although not in a power training control group. In both studies, results were less pronounced compared to the present study (4% after 6 weeks; p 0.001). In addition, Newton and McEvoy (23) showed that heavy RT for the upper body extremities helped improve BTv but that more specific RT, i.e., medicine ball throwing, had no such effect. According to the authors, medicine ball throwing was insufficiently specific with regard to movement patterns. On the other hand, heavy RT produces greater force output and rate of force development than medicine ball throwing. In fact, in medicine ball throwing, this force output is not great enough to increase the throwing velocity when using regular balls. In both 1RMBP and 4RMPS, THPs experienced significant improvements, particularly between T1-T2 (1RMBP: 16%; 4RMPS: 30.7%). In addition, it was observed that 4RMPS almost doubled increased gains when compared with the 1RMBP. Because several subjects were very young, we suggest that the squat exercise produced important muscular adaptations sufficient to result in significant increments in 4RMPS performance. After 9 weeks of heavy bench press exercise, Hoff and Almasbakk (14) also found significant increases in 1RMBP (32%; p 0.05) in 16 competition females, similar to those observed in the present investigation after 12 weeks. Furthermore, Gorostiaga et al. (11) observed that an RT group (adolescent THPs) showed an improvement in maximal strength of the leg extensors (12.2%; p 0.01) and the upper extremity muscles (pec dec: 23%; p 0.01), while observing no changes in a non-rt group (only team handball practice) and in a control group. These results reinforce those obtained in the present data, because it is more difficult to induce strength development in trained athletes compared to younger and inexperienced subjects (26). However, because the maximal strength test characteristics differed between Gorostiaga et al. (11) and our investigation, we forbear to speculate more about this issue. Earlier studies demonstrate the absence of any correlation between muscular strength and BTv (6). Subsequently, no correlation has been found between 1RMBP and BTv over different testing sessions (T1-T2, T1-T3, and T2-T3). In contrast, Hoff and Almasbakk (14) found a significant correlation between 1RMBP and BTv (r 0.88; p 0.05). It is possible that some of the improvements experienced in our study could be related to distinct factors. For example, after a heavy RT period, important neuromuscular adaptations occur (25, 26), implying a higher recruitment of motor units and an increased firing rate of motor neurons (26, 27, 34), especially in trained athletes (34). However, Fleck et al. (9) found significant correlations (p 0.05) between averages BTv with peak torque in 3 different testing speeds for shoulder horizontal abduction. In addition, these researchers also demonstrated significant correlations (p 0.05) with peak torque of shoulder flexion (300 ) and elbow extension (240 and 300 ). They suggested that an RT program in which the main object is to improve BTv should include exercises to increase torque capabilities, namely of the shoulders horizontal abductors to ensure that upper extremities could be decelerated in a controlled manner during the follow-through of the throwing motion (9, p. 24). This could be extremely important to avoid injury. For this reason, the torque produced during these movements is related to BTv (9). Several authors (6, 9, 16) also argued that BTv is able to establish a strong correlation between maximum strength developments in lower extremities. The present investigation, having demonstrated great increases in 4RMPS, suggests that a combination of powerful legs and efficient trunk rotation make for a better throw (9). This type of analysis could confirm that the main factor affecting BTv is effective energy transfer from the lower to the higher limbs (6, 16). An alternative explanation might point to the fact that the present data was carried out during a competition phase, reflecting an increased number of throws in training and competition. To reiterate, athletes often experience interruptions in training processes and competition programs (15, 18), which may result in a reduction or cessation of their normal physical activity levels (15, 18). According to Kraemer et al. (18), research investigating changes in vertical jump ability after DT period have shown no changes after 2 weeks and a 3 5% reduction after 12 weeks of DT. Previous studies claimed different results. In fact, Häkkinen and Komi (12, 13) observed significant decreases in CMJ height (p 0.05) after 24 weeks of RT followed by 12 weeks of DT. This could be due to a longer period of DT. It seems that with shorter DT periods of 2 to 6 7 weeks, jumping performance could be maintained. Kraemer et al. (18) observed that recreationally trained men can maintain jump performance during short periods of DT (6 weeks). The researchers (18) argued that other factors like jumping technique may be critical for vertical jump performance and may have contributed to the lack of change despite the reduction of performance. These results tend to be borne out by those of the present investigation in THPs. Here, subjects also showed a decline in their jump ability during DT period, although not a significant one. In our opinion, this could suggest that game-specific jumping is a better means of positively influencing jump performance in THPs (i.e., training jump shot in team handball). The maintenance of athletic performance during DT period may be also explained by

8 570 MARQUES AND GONZÁLEZ-BADILLO the continuation of specific team handball practices and competitions and, simultaneously, by the short duration of DT itself. After 4 weeks of DT, Skoufas et al. (28) observed that BTv increases were only maintained (an insignificant decrease of 0.9%) by using 20% lighter balls, suggesting that lighter weight training can be efficient in retaining performance gains. However, these results are contradicted by the present data, which showed that BTv was significantly reduced after the DT period (2.7%; p 0.05), despite coinciding with a competition phase. Several authors have proposed that strength losses incurred during DT are related to neural changes coupled with longerterm atrophic decline (18). We suggest that such decreases may be due to the incapacity of subjects to stimulate their motor units or to recruit fast twitch fibers in both explosive skills, reinforcing the hypothesis that RT absence induces significant neural losses in the muscles involved in throwing ability. It is unclear whether the inconsistency of results between different studies involving different sports is due to methodological differences, different training backgrounds, or different population characteristics. The primary limitation of this study is the absence of a control group. In practical terms, to locate a specific control group (i.e., another elite team handball sample at the same performance level of the experimental team) and to access testing conditions is not an easy task for coaches or researchers. These difficulties are compounded by the ethical problem already alluded to (17). However, such considerations ought not to detract from the necessity and importance of this type of investigation or of the present study, especially in the team handball field. The present authors speculate that the overall physical condition gains were probably due to the addition of the RT program because all subjects were in peak condition at the outset of the study. Additionally, the DT results could be a sound indicator that the previous RT program contributed to improved subject performance, especially in throwing ability, because BTv declined significantly during DT period, whereas THPs have maintained permanent throwing ability over the playoff period. Another important finding of this study was that short-term RT using moderate relative intensity tended to produce significant enhancements in THPs performance in 4RMPS and 1RMBP. In both exercises, given that the average intensity is practically the same between RT cycles (range average intensity 80% of 1RMBP and 4RMPS), the changes in volume can justify the changes in the performance. However, this is only true to the extent that prolonging the duration of training brings about progressively diminishing performance returns. According to Carpinelli and Otto (8), progressive overload is necessary for increasing muscular strength. For adaptations to occur, a stimulus in excess of previous stimuli needs to be applied during an RT program. Fry et al. (10) conceive that, once a given threshold level of strength training intensity has been reached in resistance trained athletes, the appropriate physiological adaptations may well be optimized and that training beyond this limit provides no further benefits. This statement is supported by the present findings since average intensity was equal in both of the training cycles (1 6 weeks and 7 12 weeks). In summary, THPs can increase both 1RMBP and 4RMPS using moderate volume and medium to high intensity. Therefore, the present data suggest that for health and safety reasons, increasing training volume does not always provide a better stimulus for improving adaptations during a short-term training period. In fact, trained THPs can optimize performance achieving only 30% fewer lifts tolerable at loads higher than 80% than what they achieve in maximal dynamic strength exercises. These conclusions should be interpreted within the context of the study and its sample of experienced players. PRACTICAL APPLICATIONS The present findings suggest that RT could be an important factor in positively influencing not only maximal dynamic strength performance but also jumping ability, speed, and throwing velocity performances in highly trained THPs. They also demonstrate that 7 weeks of DT were sufficient to induce significant losses in BTv but not in CMJ ability. 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