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American football is the most popular sport in the United States. Its popularity is likely related to the intense, fast-paced, physical style of play. The importance of strength and conditioning to success in football has been long understood. In fact, the strength and conditioning profession in North America can take its roots from American football. However, only recently has scientific study confirmed the positive relationships between strength, speed, and power to success in this sport. Although strength and conditioning are integral to every American football program, the collaboration with sport scientists has not been as fruitful. Only limited studies are available examining the physiological effects of actual competition and physiological adaptations or maladaptations during a season of competition. Most studies on American football have primarily focused on physical performance characteristics of these athletes and how various training paradigms can be used to improve performance.

The ultimate zone-rating extrapolation (UZR/150) rates fielding performance by runs saved or cost within a zone of responsibility in comparison with the league average (150 games) for a position. Spring-training anthropometric and performance measures have been previously related to hitting performance; however, their relationships with fielding performance measures are unknown.

The authors aimed to examine the acute hormonal and performance responses to resistance exercise with and without prior consumption of an amino acid/creatine/energy supplement. Eight men performed a resistance-exercise protocol at baseline (BL), 20 min after consuming a supplement (S) consisting of essential amino acids, creatine, taurine, caffeine, and glucuronolactone or a maltodextrin placebo (P). Venous blood samples were obtained before and immediately after (IP), 15 min (15P), and 30 min (30P) after each protocol. Area under the curve of resistance-exercise volume revealed that BL was significantly less than S (10%) and P (8.6%). For fatigue rate, only S (18.4% ± 12.0%) was significantly lower than BL (32.9% ± 8.4%). Total testosterone (TT) and growth hormone (GH) were significantly elevated at IP and 15P in all conditions. The GH response was significantly lower, however, in S and P than in BL. The TT and GH responses did not differ between S and P. These results indicated that a supplement consisting of amino acids, creatine, taurine, caffeine, and glucuronolactone can modestly improve high-intensity endurance; however, the anabolic-hormonal response was not augmented.

The purpose of this study was to examine the influence of recovery time following a dynamic warm-up (DY) and a static stretch warm-up (SS) on power performance in adolescent athletes. Following baseline measures, 19 males (16.5 ± 1.1 yrs) performed the vertical jump (VJ) and seated medicine ball toss (MB) at the following time points after DY and SS: 2, 6, 10, 14, 18, 22 min. Analysis of variance revealed that VJ was significantly greater following DY than SS at 2, 6, 10, 14 and 18 min. Main effects indicated a significant increase in VJ from baseline at 2 and 6 min following DY (2.6–3.9%) and a significant decrease in VJ from baseline at 2, 6, 10, 14 and 18 min following SS (–3.2% to –7.0%). No significant interaction effects between DY and SS were observed for MB. These findings indicate that lower body power performance in male adolescent athletes can be enhanced following DY as compared with SS during the first 18 min of the post warm-up period.

The effect of 10 wk of protein-supplement timing on strength, power, and body composition was examined in 33 resistance-trained men. Participants were randomly assigned to a protein supplement either provided in the morning and evening (n = 13) or provided immediately before and immediately after workouts (n = 13). In addition, 7 participants agreed to serve as a control group and did not use any protein or other nutritional supplement. During each testing session participants were assessed for strength (one-repetition-maximum [1RM] bench press and squat), power (5 repetitions performed at 80% of 1RM in both the bench press and the squat), and body composition. A significant main effect for all 3 groups in strength improvement was seen in 1RM bench press (120.6 ± 20.5 kg vs. 125.4 ± 16.7 at Week 0 and Week 10 testing, respectively) and 1RM squat (154.5 ± 28.4 kg vs. 169.0 ± 25.5 at Week 0 and Week 10 testing, respectively). However, no significant between-groups interactions were seen in 1RM squat or 1RM bench press. Significant main effects were also seen in both upper and lower body peak and mean power, but no significant differences were seen between groups. No changes in body mass or percent body fat were seen in any of the groups. Results indicate that the time of protein-supplement ingestion in resistance-trained athletes during a 10-wk training program does not provide any added benefit to strength, power, or body-composition changes.

The purpose of this study was to assess the lifting performance of boys (N = 12; age 11.3 ± 0.8 yr), teens (N = 13; age 13.6 ± 0.6 yr), and men (N = 17; age 21.4 ± 2.1 yr) to various rest interval (RI) lengths on the bench press exercise. Each subject performed 3 sets with a 10 repetition maximum load and a 1, 2, and 3 min RI between sets. Significant differences in lifting performance between age groups were observed within each RI for selected sets with boys and teens performing significantly more total repetitions than adults following protocols with 1 min (27.9 ± 3.1, 26.9 ± 3.9, and 18.2 ± 4.1, respectively), 2 min (29.6 ± 1.0, 27.8 ± 3.5, and 21.4 ± 4.1, respectively) and 3 min (30.0 ± 0.0, 28.8 ± 2.4, and 23.9 ± 5.3, respectively) RIs. Significant differences in average velocity and average power between age groups were also observed. These findings indicate that boys and teens are better able to maintain muscle performance during intermittent moderate-intensity resistance exercise as compared with men.

Although pre-event static stretching (SS) is an accepted practice in most youth programs, pre-event dynamic exercise (DY) is becoming popular. The purpose of this study was to examine the acute effects of pre-event SS, DY, and combined SS and DY (SDY) on vertical jump (VJ), medicine-ball toss (MB), 10-yard sprint (SP), and pro-agility shuttle run (AG) in teenage athletes (15.5 ± 0.9 years). Thirty athletes participated in three testing sessions in random order on three nonconsecutive days. Before testing, participants performed 5 min of walking/jogging followed by one of the following 10 min warm-up protocols: a) five static stretches (2 × 30 s), b) nine moderate-to-high-intensity dynamic movements (2 × 10 yards), or c) five static stretches (1 × 30 s) followed by the same nine dynamic movements (1 × 10 yards). Statistical analysis of the data revealed that performance on the VJ, MB, and SP were significantly (p < .05) improved after DY and SDY as compared with SS. There were no significant differences in AG after the 3 warm-up treatments. The results of this study indicate that pre-event dynamic exercise or static stretching followed by dynamic exercise might be more beneficial than pre-event static stretching alone in teenage athletes who perform power activities.

To examine the effect of a nutritional supplement (ATP-E™) on high intensity exercise performance, 23 physically active males volunteered to perform six Wingate Anaerobic Power tests. Tests were performed prior to and at 14 and 21 days during ATP-E~o~r placebo ingestion. f i e experiment followed a double-blind and random-order design. Twelve subjects (responders, R) showed an increase in preexercise blood ATP on Day 14 of ATP-E™ ingestion compared to control measures. The remaining 11 subjects (nonresponders, NR) had no change in pree~e~cibselo od ATP. Peak power and mean power were unchanged for both R and NR subjects across the exercise tests, but R experienced a decrease (p < 0.05) in immediate postexercise plasma lactate on Day 14 of ATP-E™ testing compared to their control measures. NR had no change in peak plasma lactate at any time during the study. The results suggest that short-term high intensity exercise performance was maintained in R with less reliance on anaerobic metabolism, and that response was evident following 14 days of ATP-E™ ingestion.

In the present study, the effects of an increased daily dose of a dietary supplement (ATP-E, 0.2 g · ${\text{kg}}^{-1}$ · ${\text{day}}^{-1}$ ) on Wingate test performance were examined in 12 men (21 ± 1.6 years) prior to and following 14 days of supplement and placebo ingestion. A double-blind and counterbalanced design was used. Results revealed higher (p < .007) preexercise blood ATP (95.4 ± 10.5 μmol · ${\text{dl}}^{-1}$ ) for the entire group following 14 days of ATP-E ingestion compared to placebo measures (87.6 ± 10.9 μmol · ${\text{dl}}^{-1}$ ). Mean power (667 ± 73 W) was higher (p < .008) after 14 days of ATP-E ingestion versus placebo (619 ± 67 W). Peak plasma lactate was lower (p < .07) after 14 days of ATP-E ingestion (14.9 ± 2.8 mmol · ${\text{L}}^{-1}$ ) compared to placebo (16.3 ± 1.6 mmol · ${\text{L}}^{-1}$ ). These data suggested that the improvement in 30-s Wingate test performance in this group may be related to the increased dose of ATP-E.