Throwing performance in shot put, javelin, hammer, and discus throw was measured outdoors (each athlete performed his/her own specialty), as previously described (11). Ambient temperature was 13–18° C at the winter tapering phase and 20–23° C at the spring tapering phase. Weather was calm and sunny during all throwing measurements. Briefly, after a short warm-up (jogging, stretching, and 2–4 near maximum throws) athletes performed 6 maximum throws. The best throwing performance was used in further analysis. To achieve competition conditions, we organized 2 regional competitions for all throwing events inviting also groups of track and field throwers from other clubs. This created a competitive spirit among the athletes leading them to achieve personal best or season best performances.
“Shot throws” is defined here as the combined performance of 2 shot put throws, which are regularly performed by all throwers: the backward overhead throw and the squat underhead throw (11). There is a strong relationship between these shot put throws and competitive throwing performance (30). These basic shot put throws were performed outdoors at similar conditions as described above. Athletes performed 4 maximum throws from each throwing test, and the best performance was used in statistical analysis. Pilot data showed a close correlation between the overhead and the underhead shot put throw (r = 0.97, p < 0.001). Thus, we decided to combine the results of these 2 tests in 1, and define it as shot throws. The intraclass correlation coefficient (ICC) for these tests was ICC = 0.91 (95% confidence interval [CI], 0.89–0.98), n = 13.
One day after performing the shot throws (described above), throwers visited the laboratory for the vertical jump tests: the squat jump (SQJ) and the countermovement jump (CMJ). All measurements were performed on a force platform (WP800, 80 × 80 cm, sampling frequency 1 kHz; Applied Measurements Ltd Co., Aldermaston, United Kingdom). Throwers started with 5 minutes warm-up on a stationary bicycle and 5 minutes stretching of the lower extremities' major muscle groups. Then, 3 CMJs with submaximal but progressively higher intensity were performed. Subsequently, 3 SQJ with maximal effort were performed (2 minutes rest between attempts) followed by 5 minutes rest and 3 CMJ with maximal effort (again, 2 minutes rest between attempts). In all attempts, hands were placed on hips. Data from the force platform were recorded and analyzed (Kyowa sensor interface PCD—320 A) to calculate the maximum vertical jump height and power output during the push off phase (8,22). The signal was filtered using a secondary low-pass Butterworth filter with a cutoff frequency of 20 Hz. The best performance in jump height was used for further analysis. The ICC for the SQJ and the CMJ were 0.90, (95% CI, 0.89–0.99) and 0.91, (95% CI, 0.90–0.99), respectively, n = 13.
Rate of Force Development
Assessment of RFD was performed 15 minutes after the vertical jump tests. Throwers were seated on a custom made steel leg press chair and placed both their feet on the force platform (WP800–1,000 kg weighting platform, 80 × 80 cm, sampling frequency 1 kHz, Applied Measurements Ltd Co.), which was positioned perpendicular, on the laboratory wall. Knee angle was set at 120° and hip angle was set at 100° (24). Athletes were instructed to apply their maximum force as fast as possible for 3 seconds. Two maximum attempts were performed with 3 minutes interval, and throwers were vocally encouraged to perform their best in each attempt. Data from the force platform were recorded (Kyowa sensor interface PCD-320 A) and analyzed. The signal was filtered using a secondary low-pass Butterworth filter with a cutoff frequency of 20 Hz. Calculations from the force-time curve included: the maximum isometric peak force, the RFD, and the impulse. Maximum isometric peak force was calculated as the greater force generated from the force-time curve. Rate of force development was calculated as the mean tangential slope of the force-time curve in specific time windows of 0–50, 0–100, 0–150, 0–200, and 0–250 milliseconds (RFD = ΔForce/ΔTime). Time intervals were chosen because of the potential relationship to force production during throwing (4,36). Impulse was calculated as the area under the force-time curve, and it represents the total force-time integral in a given time period (Impulse0-kms = ΣF0-kms × ΔTimekms, [Kms = 50, 100, 150, 200, 250]) (1). The best performance according to overall RFD was used for further statistical analysis. The ICC for the isometric peak force the RFD overall, and the impulse was ICC = 0.90, (95% CI, 0.86–0.96), 0.92, (95% CI, 0.87–0.98) and 0.93, (95% CI, 0.88–0.98), respectively, n = 13.
Repetition Maximum Strength Test
Thirty minutes after the RFD test, throwers performed the 1RM strength test on a leg press machine according to previous reports (31). Briefly, after a short warm-up, throwers performed incremental maximum efforts until they were unable to lift a heavier weight. Approximately, 3-minute rest was allowed between the trials. In all cases, 2 of the researchers were present and vocally encourage all throwers. The ICC for 1RM strength test was 0.98, (95% CI, 0.94–0.99) n = 13.
B-mode ultrasound images were recorded from the right vastus lateralis to determine its architectural characteristics (6.5 MHz Transducer; MicroMaxx Ultrasound System and Sonosite Inc., Bothell, WA, USA). Throwers were lying at a supine position with both knees extended at a resting position (18). Images were taken at 50% of the distance between the greater trochanter, and the lateral condoyle of the femur and analyzed for vastus lateralis thickness, pennation angles, and fascicle lengths (Motic Images Plus, 2.0). The ICC for muscle architecture was 0.97, (95% CI, 0.91–0.99), n = 13.
Body Composition Analysis
A total body scan was performed (Dual X-ray Absorptiometry model DPX-L; LUNAR Radiation, Madison, WI, USA) to evaluate body composition (DXA). All measurements were analyzed using the LUNAR radiation body composition program. Fat mass, lean body mass, and bone mineral density were determined for the total body in 3 different periods: at the beginning of the year-round training, after the first tapering period, and after the second tapering period. The ICC for body composition analysis was determined from 2 different researchers ICC = 0.98, (95% CI, 0.95–0.99), n = 13.
All data are represented as mean and SE. A 2-way analysis of variance for repeated measures was used to test differences before and after the tapering periods. Whenever a significant F-value was obtained, the main effects were compared with Bonferroni confidence interval adjustment. Paired samples T-Test was used to detect percent alternations differences between the LT and HT. Calculation of effect sizes (η2) was followed (9). Additionally, a 1-way repeated measures analysis of variance and Bonferroni post hoc was performed to test differences between 3-time point DXA measurements. Pearson's product moment correlation coefficient was used to explore the relationships between shot throws as well as between the initial performance and the percentage increase in performance tests of the throwers. Within subjects, variation and reliability were determined for all variables by calculating the confidence limits (95% CI) and ICC as described by Hopkins, (14). Significance was accepted at p ≤ 0.05. All statistical analysis was performed using SPSS version 17.0 software (SPSS Inc., Chicago, IL, USA).
Throwing performance increased significantly after LT by 4.8 ± 1.0% and after HT by 5.6 ± 0.9% (p = 0.001, η2 = 0.855) (Figure 2), but the difference between the 2 programs was not significant (p = 0.487, η2 = 0.052). Light-load tapering was significantly easier to perform (RPE = 4.0 ± 1.5 in LT, vs. 6.7 ± 0.9 in HT, p = 0.01, η2 = 0.757), whereas weekly training load, monotony, and strain were significantly higher for HT compared with LT (12,662 ± 816 vs. 9,360 ± 380 kg, p = 0.000, η2 = 0.763; 2.30 ± 0.01 vs. 0.71 ± 0.01, p = 0.000, η2 = 0.945; and 1,114.5 ± 86.2 vs. 424.3 ± 125.2, p = 0.000, η2 = 0.659, respectively) (Figures 3A–C). The percentage increase in shot throws was significantly different between the 2 tapering programs (0.6 ± 1.7% vs. 3.3 ± 1.9% for LT and HT, respectively, p = 0.048, η2 = 0.256; Table 4).
Jump height and power output at the SQJs and CMJs were not statistically different after tapering. However, HT induced significantly greater percentage increases in SQJ power output compared with LT (5.1 ± 2.4% vs. 0.9 ± 1.4%, p = 0.042, η2 = 0.388). No significant difference was found for leg press 1RM after LT or HT. However, the percentage increase after HT was significantly greater in comparison with LT (5.9 ± 3.2% vs. −3.4 ± 2.5%, p = 0.031, η2 = 0.415; Table 4).
No significant change was observed on isometric peak force, though, HT induced greater percentage increase in contrast to LT (17.9 ± 5.0% vs. 2.4 ± 3.1%, p = 0.016, η2 = 0.539, respectively, Table 3). In accordance, RFD and impulse remained unaltered after both tapering programs. However, HT induced greater percentage increases on RFD at 50 milliseconds (p = 0.038, η2 = 0.516), 100 milliseconds (p = 0.042, η2 = 0.418), and 200 milliseconds (p = 0.041, η2 = 0.389) in comparison with LT (Figures 4A, B), whereas, analysis of impulse demonstrated greater percentage increases after HT at 100 milliseconds (p = 0.045, η2 = 0.411), 150 milliseconds (p = 0.038, η2 = 0.512), 200 milliseconds (p = 0.044, η2 = 0.401), and 250 milliseconds (p = 0.048, η2 = 0.380, Figures 5A, B).
Muscle architecture was not altered after either tapering methods (Table 5). Lean body mass was increased significantly by 3.3 ± 0.9% after LT and 3.9 ± 0.9% after HT (p = 0.004, η2 = 0.706), compared with the measurement at the initiation of the year-round training (Table 6). There was no difference in the percentage adaptations between male and female athletes (e.g., track and field throwing performance: p = 0.87 for LT and p = 0.81 for HT). In addition, no significant correlation was found between the initial performance and the percentage increase in performance.
The main finding of this study was that track and field throwing performance increased similarly after 2 weeks of tapering either with light or heavy resistance loads in track and field throwers. Tapering with heavy loads induced, to some extent, larger increases in strength, vertical jumping, and the RFD; however, these alterations were not adequate to induce greater increases in sport-specific throwing performance compared with the LT. Training with heavy resistances also resulted in greater percentage increases in shot throws (considered as reliable tests of throwing ability, (31)) compared with LT. The latter throwing tests are simple tests with limited demands on technical skills (11,30) in contrast to the elevated technical skills necessary for sport-specific throwing performance such as the javelin or the hammer throw (11). The present results suggest that 2 weeks of tapering with HT induces somewhat better increases in strength/power compared with LT, which cannot be revealed during the performance of a technically demanding test, such as the sport-specific throwing performance. In concert with this notion, it has been shown that the increase in muscle mass/strength is not a prerequisite for an increase in performance in technically demanding efforts such as the rotational shot put throw in well-trained athletes (20). In contrast, the linear shot put throw, which is a slower and less technically demanding movement compared with the rotational shot put throw, depends to a larger degree on muscle mass/strength in well-trained shot putters (19,20).
Tapering with both 30% of 1RM and 85% of 1RM was performed with maximum intentional speed of movement. Training with 30% of 1RM increases throwing performance, muscle strength and power, and the cross-sectional area (CSA) of type IIx quadriceps muscle fibers, whereas the percentage of these fibers remains unchanged, at least in novice throwers (35). In a similar context, it has been described that training with heavy loads (>80% of 1RM) and maximum intentional movement velocity increases strength, power, and RFD in untrained subjects (34). This type of training has been also linked to an increase in the recruitment of high threshold motor units, which suggests specific neural adaptations (10), although the complete neuromuscular adaptations induced by this type of training remain largely unexplored. It is obvious that both of these training intensities can induce significant adaptations leading to muscle power development. Indeed, the present results reveal that despite small differences in power development, both LT and HT can be effective in increasing track and field throwing performance after only 2 weeks of tapering. Unfortunately, we were not able to evaluate specific neuromuscular adaptations such as the muscle fiber composition or the electromyographic activity after the HT and LT, which it would provide valuable information for the interpretation of the current results.
Tapering with 85% of 1RM induced greater percentage increases in leg press strength compared with LT, although it should be considered that the leg press may not be the best test to evaluate muscular strength in throwers, regarding movement specificity. This might be attributed to the sudden reduction in training volume and intensity with 2 weeks of LT compared with the precompetition training, which has been linked to type II muscle fibers' atrophy (e.g., after 14 days of detraining in power athletes, 15). In contrast, in HT the training volume and intensity remained comparable with the precompetition training period. Similar to the changes in muscle strength, HT resulted in greater increases in RFD compared with LT. Rate of force development is thought to be depended on muscle mass, muscle fiber composition, and neural drive (1). Andersen et al. (2) suggested that the principal training stimulus for increasing RFD is high resistance with the highest intended movement velocity, as performed in the HT program of this study. This might explain the small difference in RFD in favor of the HT program. As shown before, power production during vertical jumping is increased between the preseason and the competition phase in well-trained throwers (19). Actually, a significant correlation has been found between shot put throwing performance and vertical jump power output in trained shot putters (r = 0.66, p ≤ 0.05 (19)). In this study, the percentage increase of power output during the SQJ after HT was significantly greater in contrast to LT, which again reveals a closer link between HT and throwing performance. Unfortunately, scarce data exist on the alternations of RFD after short-term tapering in athletes. Alterations in RFD after tapering need further investigation.
Muscle mass is a crucial factor, which contributes to performance in power demanding sports. Lean body mass correlates well with track and field throwing performance in novice throwers (31), although it cannot predict performance among experienced shot put athletes (20). The year-round training increased the total body lean mass by approximately 3.5%, similarly to previous reports in throwers (20), which states the effectiveness of the total training program. However, measurement of the vastus lateralis thickness with ultrasound before and after the tapering periods did not reveal significant alterations, whereas DXA was not performed before and after these periods. Although small changes in muscle mass cannot be excluded, it seems that 2 weeks of tapering is a short period to detect such changes in trained individuals, thus it cannot be a valid measure of muscle adaptations in similar cases.
Moreover, muscle architecture did not reveal any differential effects between the 2 tapering modes. Ultrasonography revealed no significant changes in vastus lateralis muscle architecture after either tapering methods. It is possible that 2 weeks of training was a short time to detect differences in muscle architecture, if any. In a previous study with 5 weeks of resistance training, fascicle length and fascicle angle were slightly increased, whereas the opposite results were found with high-velocity training in vastus lateralis (6). However, in this study, the short training duration might have rendered impossible to detect such changes in muscle architecture.
The magnitude of performance increases after tapering, which was found in this study (4.8% after LT and 5.6% after HT [95% CI, −3.48 to 1.76]) was similar to that found in previous studies in different sport events such as swimming, running, and rowing (27). Similar increases in shot put performance in experienced athletes (4.7% (19)), or college athletes (5.4% (29)) have been reported before and after several weeks of training, which included the preparatory training phase and the tapering phase. As a final point regarding the performance enhancement found in this study, the difference in improvements after LT and HT was nonsignificant (0.8%). However, this difference in the training response might be of importance for the coach and athlete because it might make the difference between the first and the second place in the major competition. Considering this, as well as the somewhat larger effect of the HT on muscular strength, jumping, and RFD, more research should be focused on the effectiveness of LT vs. HT in power events such as the track and field throws, perhaps including longer tapering periods and well-trained athletes competing in the same event.
In conclusion, 2 weeks of tapering with 30% of 1RM or 85% of 1RM, performed with maximum intentional velocity, leads to similar increases on throwing performance in young track and field throwers. Tapering with heavy loads induces superior increases in muscular strength, jumping performance, and RFD, but tapering with lower loads is easier to perform.
The results of this study suggest that 2 weeks of tapering with 30% of 1RM or 85% of 1RM increases performance in track and field throwers similarly by 4–6%. Training with either light or heavy loads should be performed with maximal intentional movement velocity. Additionally, when one of the central training goals of the tapering period is to increase strength and power (in addition to the increase in throwing performance) training with 85% of 1RM should be preferred over 30% of 1RM. Tapering with 30% of 1RM is easier to perform than tapering with 85% of 1RM, hence this method can be used effectively to increase the throwing performance when the athlete is experiencing light injuries or has the feeling of tiredness after the long preparation phase. As a final point, it should be noted that the expected performance changes after tapering are the result of both the preparatory training period preceding the taper and the training during tapering itself. Therefore, these 2 training periods should be considered as a continuum and at an individualized manner to achieve the best possible performance increase at competition.
The authors express our gratitude to the athletes who participated in the study. The authors also thank Dr. Stavros Kavouras for the DXA measurements.
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Keywords:Copyright © 2014 by the National Strength & Conditioning Association.
strength/power training; shot put; discus; hammer; javelin; rate of force development