Postcompetition elevation of muscle enzyme levels in professional football players

Strenuous exercise causes a rise in circulating levels of creatine kinase (CK), and well-trained athletes liberate smaller amounts than do untrained individuals. Plasma CK, aspartate aminotransferase, and lactate dehydrogenase were measured in a group of 23 professional football players 48 hours after competition. All players were asymptomatic for myalgias or chest discomfort despite elevations of CK levels. Physicians should be aware of these elevations in muscle enzymes postexertion and interpret each in conjunction with the athlete's symptoms.     

Hamstring muscle architecture and myotonometer measurements in elite professional football players with a prior strained hamstring

The purpose of this study was to compare the fascicle length, angle pennation and mechanical properties of the biceps femoris long head (BFlh) in dominant and non-dominant limbs in previously injured and uninjured professional football players. Fifteen professional football players were recruited to participate in this study. Seven players had suffered a BFlh injury during the previous season. Myotonometry mechanical properties were measured in the proximal, common tendon and distal BFlh using MyotonPRO, and angle pennation and fascicle length were also measured. We observed significantly higher distal BFlh frequency, stiffness, decrement, relaxation and creep than in the common tendon and proximal BFlh. The previously injured players showed significantly higher frequency and stiffness, and lower relaxation and creep in the dominant BFlh than did uninjured players. There were no significant differences between the fascicle length and angle pennation in previously injured and uninjured BFlh. Myotonometric measurement provides a quick and inexpensive way to check the properties of the BFlh in professional football players. Professional football players with previous BFlh injury showed higher intrinsic tension and a poorer capacity to deform than did players with no injury to the BFlh.     

Comparison between linear and nonlinear in-season training programs in freshman football players

The purpose of this study was to compare linear (LT) with nonlinear (NL) in-season training programs in freshman football players during the course of 2 separate seasons. During the first year (n = 14, mean +/- SD = 177.3 +/- 4.8 cm, 88.0 +/- 9.7 kg), the LT program was employed 2 days per week. In the second year (n = 14, 175.0 +/- 7.1 cm, 94.2 +/- 20.5 kg), a 2 days per week LT was used. Subjects were tested for maximal strength in the squat (1 repetition maximum [1RM]) and bench press (1RM) exercises. A significant improvement in 1RM squat was seen in LT, but not in NL. No significant improvement in 1RM bench press was seen in either group. A significant difference between LT and NL was observed in Delta1RM squat (13.8 +/- 7.4 kg compared with 1.6 +/- 2.6 kg, respectively). Results of this study suggest that LT may be more effective in eliciting strength gains than NL in freshman football players during an in-season training program.     

In-season resistance training and detraining in professional team handball players

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.     

Changes in strength over a 2-year period in professional rugby union players

The purpose of this study was to assess the magnitude of upper and lower body strength changes in highly trained professional rugby union players after 2 years of training. An additional purpose was to examine if the changes in strength were influenced by the starting strength level, lean mass index (LMI), or chronological age. This longitudinal investigation tracked maximal strength and body composition over 3 consecutive years in 20 professional rugby union athletes. Maximal strength in the bench press and back squat and body composition was assessed during preseason resistance training sessions each year. The athletes completed a very rigorous training program throughout the duration of this study consisting of numerous resistance, conditioning and skills training sessions every week. The primary findings of this study were as follows: (a) Maximal upper and lower body strength was increased by 6.5-11.5% after 2 years of training (p = 0.000-0.002 for bench press; p = 0.277-0.165 for squat); (b) magnitude of the improvement was negatively associated with initial strength level (r = -0.569 to -0.712, p ≤ 0.05); (c) magnitude of improvement in lower body maximal strength was positively related to the change in LMI (an indicator of hypertrophy; r = 0.692-0.880, p ≤ 0.05); and (d) magnitude of improvement was not associated with the age of professional rugby union athletes (r = -0.068 to -0.345). It appears particularly important for training programs to be designed for continued muscle hypertrophy in highly trained athletes. Even in professional rugby union athletes, this must be achieved in the face of high volumes of aerobic and skills training if strength is to be increased.     

Comparison of Olympic vs. traditional power lifting training programs in football players

Twenty members of an National Collegiate Athletic Association Division III collegiate football team were assigned to either an Olympic lifting (OL) group or power lifting (PL) group. Each group was matched by position and trained 4-days.wk(-1) for 15 weeks. Testing consisted of field tests to evaluate strength (1RM squat and bench press), 40-yard sprint, agility, vertical jump height (VJ), and vertical jump power (VJP). No significant pre- to posttraining differences were observed in 1RM bench press, 40-yard sprint, agility, VJ or in VJP in either group. Significant improvements were seen in 1RM squat in both the OL and PL groups. After log10-transformation, OL were observed to have a significantly greater improvement in Delta VJ than PL. Despite an 18% greater improvement in 1RM squat (p > 0.05), and a twofold greater improvement (p > 0.05) in 40-yard sprint time by OL, no further significant group differences were seen. Results suggest that OL can provide a significant advantage over PL in vertical jump performance changes.     

An intensive combined training program modulates physical, physiological, biomotoric, and technical parameters in women basketball players

The purpose of this study was the investigation of the effects of an intensive combined training program based on the pretest scores of a university women's basketball team on their physical, physiological, biomotoric, and technical features. Twenty-four university volunteers were equally divided into two groups: an experiment group (intensive combined training group) and a control (technical training) group. The 10-week intensive combined training program was performed on the experiment group according to their pretest outcomes. Before and at the end of each period of training, which was scheduled four times a week, the physical, physiological, biomotoric, and technical performance of each subject were determined. With respect to the pre- and posttest measurements, the basketball group showed significant differences (p < 0.05) in girth measurements (shoulder, waist, hip, arm, thigh, and calf), in skinfold measurements (percent body fat), in physiological measurements (vital capacity and forced vital capacity), in biomotoric tests (right-left hand grip, dynamic and countermovement jump, sit-up, push-up, 1500-m endurance), and in technique tests (free and inside shooting). It can be concluded that a 10-week intensive combined training program performed on university women basketball players had a significant effect on improving their physical, physiological, biomotoric, and technical features. It proved to be highly recommendable for female basketball players who are preparing for short-term tournaments; the basketball group in this study won a championship.     

少年足球运动员运动性疲劳后的差异代谢物筛选

目的:探索少年足球运动员在运动性疲劳后的差异代谢物变化。方法:以12名男性少年足球运动员(14～16岁)为试验对象,用功率自行车建立包含有氧运动和无氧运动的训练模型:完成6 min 150 W负荷、60～65r/min的踏骑运动和30 s的负荷按照测试者体重而设定的最大速度踏骑运动,中间休息1 min,重复运动3组,组间休息3 min;测定运动员每组运动后的最大摄氧量值和平均无氧功率值,采集运动训练前后的尿液样本,利用气相-质谱联用(GC-MS)法检测尿液样本,通过数据库筛选潜在的差异代谢物。结果:与运动前相比较,少年足球运动员运动疲劳后的平均无氧功率显著下降(P<0.05),筛选出25个差异代谢物,其中3个代谢物显著升高(P<0.05,0.01),22个代谢物显著降低(P<0.05,0.01);上述差异代谢物的相关代谢通路归属为甘氨酸-丝氨酸-苏氨酸代谢、三羧酸循环、酪氨酸代谢、氮代谢和甘油磷酯代谢通路。结论:少年足球运动员发生运动性疲劳后,机体的代谢物:肌氨酸、L-别苏氨酸、肌酸、丝氨酸、琥珀酸、柠檬酸、4-羟基苯乙酸、羟胺和乙醇胺产生明显的变化,上述差异代谢物可...     

Effects of in-season strength maintenance training frequency in professional soccer players

The aim of the present study was to examine the effect of in-season strength maintenance training frequency on strength, jump height, and 40-m sprint performance in professional soccer players. The players performed the same strength training program twice a week during a 10-week preparatory period. In-season, one group of players performed 1 strength maintenance training session per week (group 2 + 1; n = 7), whereas the other group performed 1 session every second week (group 2 + 0.5; n = 7). Only the strength training frequency during the in-season differed between the groups, whereas the exercise, sets and number of repetition maximum as well as soccer sessions were similar in the 2 groups. The preseason strength training resulted in an increased strength, sprint, and jump height (p < 0.05). During the first 12 weeks of the in-season, the initial gain in strength and 40-m sprint performance was maintained in group 2 + 1, whereas both strength and sprint performance were reduced in group 2 + 0.5 (p < 0.05). There was no statistical significant change in jump height in any of the 2 groups during the first 12 weeks of the in-season. In conclusion, performing 1 weekly strength maintenance session during the first 12 weeks of the in-season allowed professional soccer players to maintain the improved strength, sprint, and jump performance achieved during a preceding 10-week preparatory period. On the other hand, performing only 1 strength maintenance session every second week during the in-season resulted in reduced leg strength and 40-m sprint performance. The practical recommendation from the present study is that during a 12-week period, 1 strength maintenance session per week may be sufficient to maintain initial gain in strength and sprint performance achieved during a preceding preparatory period.     

Heat acclimatization and hydration status of American football players during initial summer workouts

This investigation evaluated the new National Collegiate Athletic Association model of heat acclimatization for football players using physiological, psychological, fluid balance, anthropometric, and nutritional variables. Eleven football players (20 +/- 1 year, 1.88 +/- 0.05 m, and 115.36 +/- 18.85 kg) from a Division I football team were observed for the first 8 days of preseason practices. Measurements such as heart rate and gastrointestinal temperature (T(GI)) via telemetric sensor were taken before, 3 times during, and after practice daily. An average 1.39-kg (1.2%) decrease of body mass occurred from prepractice to postpractice (p < 0.01). Consistent with mild body mass losses, urinary indices of hydration status (i.e., color, specific gravity, and osmolality) indicated mild fluid deficits. A significant increase (p < 0.05) from pre- to postpractice was observed in urine color and urine specific gravity, but chronic hypohydration over the 8 days was not noted. The Environmental Symptoms Questionnaire (ESQ) postpractice score was significantly higher (p < 0.05) than the prepractice score was, but averages did not differ across practice days. There was no difference in postpractice T(GI) measurements across days (p < 0.05). Heart rate, T(GI), and ESQ measurements indicated that football players experienced gradual heat acclimatization and enhanced heat tolerance, despite progressive increases of exercise variables, clothing, and environmental stressors.     

4周低氧训练对男子足球运动员有氧耐力与T淋巴细胞亚群的影响

目的：探讨4周低氧训练对男子足球运动员有氧耐力相关指标与免疫系统中T淋巴细胞亚群的影响。方法：选取某体育学院及其附属竞技学校20名男子足球运动员为受试者,平均分为训练组、低氧组、低氧训练组以及对照组。训练组进行每日60 min,每周5次,持续4周的功率自行车训练,运动强度为65%~75%最大摄氧量;低氧组进行持续4周每日60 min,每周5次处于低氧环境（氧浓度为14.7%）,不进行功率自行车训练;低氧训练组在低氧环境（氧浓度为14.7%）下进行与训练组相同条件的训练;对照组不做任何影响。结果：经4周训练后,低氧训练组红细胞计数、血红蛋白含量较对照组、训练组以及低氧组均存在显著性差异（P < 0.05）;低氧训练组VO₂max水平和3 000 m跑成绩较对照组、训练组以及低氧组均存在显著性差异（P < 0.05）;低氧训练组T淋巴细胞CD3⁺水平较对照组、低氧组均存在显著性差异（P < 0.05）。结论：相比于其他方式,每日60 min,每周5日,持续4周的65%~75%最大摄氧量强度低氧训练更有利于提高男子足球运动员的有氧耐力水平,并且可能有利于运动员机体免疫功能的提高。     

The anaerobic endurance of elite soccer players improved after a high-intensity training intervention in the 8-week conditioning program

The purpose of this study was to evaluate changes in anaerobic endurance in elite First-league soccer players throughout 2 consecutive seasons, in 2 phases, with and without high-intensity situational drills. Eighteen soccer players were tested before and after the 8-week summer conditioning and again in the next season. The measured variables included 300-yard shuttle run test, maximal heart rate, and maximal blood lactate at the end of the test. During the first phase of the study, the traditional sprint training was performed only 2 x weeks and consisted of 15 bouts of straight-line sprinting. In the second year the 4 x 4 min drills at an intensity of 90-95% of HRmax, separated by periods of 3-minute technical drills at 55-65% of HRmax were introduced. Statistical significance was set at P 相似文献   

The effects of a 10-week,periodized, off-season resistance-training program and creatine supplementation among collegiate football players

The periodized resistance-training model has not been well documented in the literature. Further research is needed to determine if periodized resistance training in conjunction with creatine supplementation can cause changes in strength, performance, total body weight, girth, and lean muscle mass. Therefore, the purpose of this investigation was to determine the effects of periodized resistance training in conjunction with low-dose (LD) and high-dose (HD) creatine supplementation on strength, body composition, and anaerobic muscular endurance. Subjects were divided into 3 groups: LD, HD, and placebo (P). Testing took place pre-, mid-, and postsupplementation for the following: weight, body composition (fat-free mass and fat mass), 1 repetition maximum squat, and anaerobic muscular endurance testing. Results revealed no significant differences in either creatine group when compared with the P group. However, significant differences were noted over time. These data suggest that 10 weeks of periodized resistance training was effective for causing changes in strength, body composition, and anaerobic muscular endurance.     

Comparison of loaded and unloaded jump squat training on strength/power performance in college football players

The purpose of this study was to explore the effects of 5 weeks of eccentrically loaded and unloaded jump squat training in experienced resistance-trained athletes during the strength/ power phase of a 15-week periodized off-season resistance training program. Forty-seven male college football players were randomly assigned to 1 of 3 groups. One group performed the jump squat exercise using both concentric and eccentric phases of contraction (CE; n = 15). A second group performed the jump squat exercise using the concentric phase only (n = 16), and a third group did not perform the jump squat exercise and served as control (CT; n = 16). No significant differences between the groups were seen in power, vertical jump height, 40-yd sprint speed and agility performance. In addition, no differences between the groups were seen in integrated electromyography activity during the jump squat exercise. Significant differences between the CE and CT groups were seen in Delta 1RM squat (65.8 and 27.5 kg, respectively) and Delta 1RM power clean (25.9 and 3.8 kg, respectively). No other between-group differences were observed. Results of this study provide evidence of the benefits of the jump squat exercise during a short-duration (5-week) training program for eliciting strength and power gains. In addition, the eccentric phase of this ballistic movement appears to have important implications for eliciting these strength gains in college football players during an off-season training program. Thus, coaches incorporating jump squats (using both concentric and eccentric phases of contraction) in the off-season training programs of their athletes can see significant performance improvements during a relatively short duration of training.     

Effects of a plyometric training program with and without added load on jumping ability in basketball players

The purpose of this investigation was to examine the effect of a standard plyometric training protocol with or without added load in improving vertical jumping ability in male basketball players. Twenty-seven players were randomly assigned to 3 groups: a control group (no plyometric training), plyometric training group (PG), and loaded plyometric group (LPG, weighted vests 10-11% body mass). Before and after the 10-week training program, all the players were tested for the 5-jump test (5JT), the squat jump (SJ), and the countermovement jump (CMJ). The PG and LPG groups performed 2 and 3 training sessions per week, during the first 3 and the last 7 weeks, respectively. The results showed that SJ, CMJ, and 5JT were significantly improved only in the PG and LPG groups. The best effects for jumps were observed in LPG (p < 0.01), which showed significantly higher gains than the PG (p < 0.05). In conclusion, it appears that loads added to standard plyometric training program may result in greater vertical and horizontal-jump performances in basketball players.     

Short-term effects of strength and plyometric training on sprint and jump performance in professional soccer players

The purpose of this study was to compare the effects of combined strength and plyometric training with strength training alone on power-related measurements in professional soccer players. Subjects in the intervention team were randomly divided into 2 groups. Group ST (n = 6) performed heavy strength training twice a week for 7 weeks in addition to 6 to 8 soccer sessions a week. Group ST+P (n = 8) performed a plyometric training program in addition to the same training as the ST group. The control group (n = 7) performed 6 to 8 soccer sessions a week. Pretests and posttests were 1 repetition maximum (1RM) half squat, countermovement jump (CMJ), squat jump (SJ), 4-bounce test (4BT), peak power in half squat with 20 kg, 35 kg, and 50 kg (PP20, PP35, and PP50, respectively), sprint acceleration, peak sprint velocity, and total time on 40-m sprint. There were no significant differences between the ST+P group and ST group. Thus, the groups were pooled into 1 intervention group. The intervention group significantly improved in all measurements except CMJ, while the control group showed significant improvements only in PP20. There was a significant difference in relative improvement between the intervention group and control group in 1RM half squat, 4BT, and SJ. However, a significant difference between groups was not observed in PP20, PP35, sprint acceleration, peak sprinting velocity, and total time on 40-m sprint. The results suggest that there are no significant performance-enhancing effects of combining strength and plyometric training in professional soccer players concurrently performing 6 to 8 soccer sessions a week compared to strength training alone. However, heavy strength training leads to significant gains in strength and power-related measurements in professional soccer players.     

Physical demands of National Collegiate Athletic Association Division I football players during preseason training in the heat

The purpose of this study was to evaluate physical demands of football players during preseason practices in the heat. Furthermore, we sought to compare how physical demands differ between positions and playing status. Male National Collegiate Athletic Association Division 1 football players (n = 49) participated in 9 practice sessions (142 ± 16 minutes per session; wet bulb globe temperature (WBGT) 28.75 ± 2.11°C) over 8 days. Heart rate (HR) and global positioning system data were recorded throughout the entirety of each practice to determine the distance covered (DC), velocity (V), maximal HR (HRmax), and average HR (HRavg). The subjects were divided into 2 groups: linemen (L) (N = 25; age: 22 ± 1 years, weight: 126 ± 16 kg, height: 190 ± 4 cm,) vs. nonlinemen (NL) (N = 24; age: 21 ± 1 years, weight: 91 ± 11 kg, height: 183 ± 8 cm) and starters (S) (N = 17; age: 21 ± 1 years, weight: 118 ± 21 kg, height: 190 ± 7 cm) vs. nonstarters (NS) (N = 32; age: 20 ± 1 years, weight: 105 ± 22 kg, height: 185 ± 7 cm) for statistical analysis. The DC (3,532 ± 943 vs. 2,573 ± 489 m; p = 0.001) and HRmax (201 ± 9 vs. 194 ± 11 b·min(-1); p = 0.025) were significantly greater in NL compared with that in L. In addition, NL spent more time (p < 0.0001) and covered more distance (p = 0.002) at higher velocities than L did. Differences between S vs. NS were observed (p = 0.008, p = 0.031), with S obtaining higher velocities than NS did. Given the demands of their playing positions, NL were required to cover more distance at higher velocities, resulting in a greater HRmax than that of L. Therefore, it appears that L engage in more isometric work than NL do. In addition, the players exposed to similar practice demands provide similar work output during preseason practice sessions regardless of their playing status.