Pre-sleep feeding, sleep quality, and markers of recovery in division I NCAA female soccer players.

Pre-sleep nutrition habits in elite female athletes have yet to be evaluated. A retrospective analysis was performed with 14 NCAA Division I female soccer players who wore a WHOOP, Inc. band - a wearable device that quantifies recovery by measuring sleep, activity, and heart rate metrics through actigraphy and photoplethysmography, respectively - 24 h a day for an entire competitive season to measure sleep and recovery. Pre-sleep food consumption data were collected via surveys every 3 days. Average pre-sleep nutritional intake (mean ± sd: kcals 330 ± 284; cho 46.2 ± 40.5 g; pro 7.6 ± 7.3 g; fat 12 ± 10.5 g) was recorded. Macronutrients and kcals were grouped into high and low categories based upon the 50th percentile of the mean to compare the impact of a high versus low pre-sleep intake on sleep and recovery variables. Sleep duration (p = 0.10, 0.69, 0.16, 0.17) and sleep disturbances (p = 0.42, 0.65, 0.81, 0.81) were not affected by high versus low kcal, PRO, fat, CHO intake, respectively. Recovery (p = 0.81, 0.06, 0.81, 0.92), RHR (p = 0.84, 0.64, 0.26, 0.66), or HRV (p = 0.84, 0.70, 0.76, 0.93) were also not affected by high versus low kcal, PRO, fat, or CHO consumption, respectively. Consuming a small meal before bed may have no impact on sleep or recovery.

Comparison of VO2peak from the Progressive Aerobic Cardiovascular Endurance Run (PACER) and treadmill in children.

Background/Objectives: The purpose of this study was to investigate the difference in peak oxygen consumption (VO2peak) during a graded treadmill test and the Progressive Aerobic Cardiovascular Endurance Run (PACER) in a sample of 7-14 year old children. Methods: Forty-four participants (25 boys, 19 girls) had VO2 assessed during a peak treadmill test and the PACER by a portable indirect calorimeter on non-consecutive days. Exercise parameters were compared between exercise tests by paired t-tests. Results: The PACER elicited a greater measured VO2peak (49.4 ± 9.4 vs. 46.7 ± 7.5 ml. kg-1·min-1) and maximum respiratory exchange ratio (1.14 ± 0.08 vs. 1.07 ± 0.08) than the treadmill test (p < 0.05). Rating of perceived exertion was higher (8.1 ± 3.5 vs 7.6 ± 3.8) during the treadmill test compared to the PACER test (p < 0.05). There was no difference in maximum heart rate between treadmill test and PACER test (196.9 ± 9.3 vs. 198.6 ± 8.8, p > 0.05). Conclusions: The PACER provides an acceptable measure of cardiorespiratory fitness in children but the finding that children elicit a higher measured VO2peak during the PACER compared to a graded treadmill test warrants continual refinement in future aerobic fitness prediction equations from the PACER.

Combined Sprint Interval, Plyometric, and Strength Training in Adolescent Soccer Players: Effects on Measures of Speed, Strength, Power, Change of Direction, and Anaerobic Capacity.

Ferley, DD, Scholten, S, and Vukovich, MD. Combined sprint interval, plyometric, and strength training in adolescent soccer players: effects on measures of speed, strength, power, change of direction, and anaerobic capacity. J Strength Cond Res 34(4): 957-968, 2020-During winter, many soccer players train indoors to improve the aerobic and anaerobic demands of their sport. Sprint interval training (SIT) performed on a treadmill using level and graded conditions represents a viable alternative to traditional endurance conditioning. To date, little research exists contrasting the effects of these conditions. Therefore, the purpose of this investigation included examining the effects of 2 approaches combining SIT, plyometrics, and strength training on performance measures in soccer players aged 13-18 years over 8 weeks. Forty-six subjects were divided into 3 groups. Group 1 performed SIT using predominantly inclined treadmill conditions combined with resistance and plyometric training (INC, n = 17). Group 2 performed SIT using level treadmill grades and completed the same resistance and plyometric training (LEV, n = 14). Group 3 was a control group representing various sports who continued their normal training (CON, n = 15). Pre- and posttests assessed speed, strength, change of direction, and anaerobic capacity, including sprint speed (9.1 and 18.3 m sprint), unilateral triple hop for distance (3HOP_L and 3HOP_R), pro agility change of direction (PA); treadmill running to exhaustion on a 20% grade (CFMod), and hip flexor maximum strength (HF_1RM). After training, INC and LEV improved more in all measures compared with CON. Furthermore, INC improved significantly more compared with LEV in 9.1- and 18.3-m sprint, 3HOP_L and 3HOP_R, PA, CFMod, and HF_1RM (p < 0.05). We conclude that strength and plyometric training combined with incline-based SIT is more effective than a similar training approach using level-grade SIT.

Predicting the Intensity for Performing Supramaximal Incline Treadmill Interval Training in Distance Runners.

Ferley, DD and Vukovich, MD. Predicting the intensity for performing supramaximal incline treadmill interval training in distance runners. J Strength Cond Res 33(5): 1354-1361, 2019-Recent evidence highlights the effectiveness of 30-second bouts paired with level-grade supramaximal interval training (SMIT) and incline treadmill training (INC), respectively, in distance runners. Although INC has been described as a form of SMIT, no investigation of INC involving a supramaximal intensity and 30-second bouts has occurred; hence, no established recommendation for prescribing a supramaximal intensity with 30-second bouts for INC exists. Therefore, the purpose of this investigation included reporting on the time-to-exhaustion (Tmax) response and test-retest reliability of running on a 5% grade using supramaximal intensities of 110, 115, 120, 125, and 130% of the velocity associated with maximum oxygen consumption (Vmax). Additionally, these measures were assessed during 140% Vmax and 1% grade. A second aim included determining the %Vmax associated with a 30-second effort via bivariate analysis. Twelve distance runners (age, 26.9 ± 4.8 years; body mass, 69.2 ± 11.7 kg; height, 177.3 ± 10.2 cm; and V[Combining Dot Above]O2max, 61.4 ± 6.3 ml·kg·min) completed 2 Tmax trials at each intensity for measures of reliability. The dependent variable was the Tmax of each condition. Statistical significance was set to p ≤ 0.05. Student's t-test revealed no significant differences between trials for all intensities. One-way analysis of variance revealed (a) that Tmax during INC at 110% Vmax was significantly different than all conditions except 115% Vmax and (b) no significant difference in Tmax between 120, 125, 130, and 140% Vmax conditions. In conclusion, Tmax of all conditions proved reliable, and bivariate analysis revealed running at 125% Vmax on a 5% grade yielded a 30-second effort.

Assessing the Reliability of Using a Horizontal Leg Press Equipped With a Force Plate to Report on Measures of Positive and Negative Neuromuscular Characteristics.

Ferley, DD and Vukovich, MD. Assessing the reliability of using a horizontal leg press equipped with a force plate to report on measures of positive and negative neuromuscular characteristics. J Strength Cond Res 33(2): 360-371, 2019-Individuals participating in sport or returning from a lower-extremity injury routinely perform assessments of lower-body anaerobic capacity and power to gauge fitness or readiness to return to competition. However, many commonly used assessments lack the specificity of movement and muscle contraction demonstrated in sprinting, jumping, and changing direction. Therefore, this investigation assessed the reliability of a novel lower-body power test called a Plyo Press Power Quotient (3PQ), which involves jumping on a horizontal leg press equipped with a force plate. Thirty participants completed 1 repetition maximum (1RM) strength testing for 1 and 2 legs and a countermovement vertical jump. Two trials of 1- and 2-leg jump tests were performed using 30, 40, 50, and 60% of 1RM for 20 and 30 seconds, respectively. Dependent variables were a variety of positive (concentric) and negative (eccentric) neuromuscular indices. Statistical significance was set to p ≤ 0.05. No significant differences existed between trial 1 and 2 for any measures. One-way analysis of variance between %1RM conditions revealed significant differences in peak force (right; both), average negative power (left; right), average negative work (left; right), rate of power development (both), percent positive and negative fatigue (left; right; both), and velocity of movement (left; right; both). Peak power of all 2-leg jump tests correlated highly with vertical jump (r ≥ 0.89) but was significantly different. We conclude 3PQ testing provides a reliable assessment of anaerobic capacity and power, with the added benefit of easy single-leg comparisons.

The Effect of Nitrate Supplementation on Exercise Tolerance and Performance: A Systematic Review and Meta-Analysis.

Van De Walle, GP and Vukovich, MD. The effect of nitrate supplementation on exercise tolerance and performance: a systematic review and meta-analysis. J Strength Cond Res 32(6): 1796-1808, 2018-The purpose of this article was to systematically review the current literature and evaluate the overall efficacy of nitrate supplementation on exercise tolerance and performance by meta-analysis. Studies were eligible for inclusion if they met the following criteria: (a) were an experimental trial published in an English peer-reviewed journal; (b) compared the effects of inorganic nitrate consumption with a non-bioactive supplement control or placebo; (c) used a quantifiable measure of exercise performance; and (d) was carried out in apparently healthy participants without disease. A total of 29 studies were identified that investigated the effects of nitrate supplementation on exercise tolerance or performance in accordance with the criteria outlined. Analysis using time to exhaustion as the outcome variable revealed a significant effect of nitrate supplementation on exercise tolerance (ES = 0.28; 95% confidence interval [CI]: 0.08-0.47; p = 0.006) compared with placebo. Analysis using time to complete a specific distance as the outcome variable revealed no significant effect of nitrate supplementation on exercise performance (ES = -0.05; 95% CI: -0.28 to 0.17; p = 0.64) compared with placebo. Nitrate supplementation is likely to improve exercise tolerance and capacity that may improve exercise performance. More research is required to determine the optimal dose and duration of nitrate supplementation. It would also be important to consider the type of athlete performing the exercise and the duration, intensity, and mode of the exercise performed because these factors are likely to influence the efficacy of nitrate supplementation.

Protein Supplementation During a 6-Month Concurrent Training Program: Effect on Body Composition and Muscular Strength in Sedentary Individuals.

We examined the effect of a protein supplement on muscular strength and body composition during 6 months of a 5 days/week concurrent strength and endurance training program. Sedentary males (n = 26) and females (n = 25), 18-25 years, were randomly assigned to receive a protein (PRO, 42 g/serving) or carbohydrate (CON) supplement twice daily. Strength and body composition (dual-energy X-ray absorptiometry) were assessed at baseline, 3 (3M), and 6 (6M) months. Protein intake was higher in PRO (PRO: 2.2 g/kg; CON: 1.1 g/kg; p < .001). Females in both groups gained similar strength at 3M and 6M in bench press and hip sled. Males in PRO gained more bench press strength at 3M (PRO: 24.6 ± 3.2 kg; CON: 14.3 ± 3.8 kg; p = .06) and 6M (PRO: 34.4 ± 4.3 kg; CON: 18.7 ± 5.1 kg; p = .03) and hip sled strength at 3M (PRO: 67.7 ± 9.2 kg; CON: 40.8 ± 10.8 kg, p = .07) and 6M (PRO: 94.0 ± 10.6 kg; CON: 65.1 ± 12.4 kg; p = .09) compared with CON. Females in PRO experienced a greater reduction in fat mass over the course of the study (6M) than CON (PRO: -1.7 ± 0.5 kg; CON: 0.1 ± 0.5 kg; p = .06). Changes in lean mass were similar for females in PRO and CON. Loss in fat mass was similar for males in PRO and CON at 3M and 6M. Males in PRO gained more lean mass at 3M compared with CON (PRO: 3.2 ± 0.3 kg; CON: 2.2 ± 0.4 kg; p = .1) but similar gains at 6M (PRO: 2.6 ± 0.4 kg; CON: 2.2 ± 0.5 kg; p = .6). The results of this study demonstrate that PRO used during a concurrent training program may augment positive changes in body composition in young sedentary males and females, and strength gains in males.

The effect of six days of dietary nitrate supplementation on performance in trained CrossFit athletes.

BACKGROUND: While it is well established that dietary nitrate reduces the metabolic cost of exercise, recent evidence suggests this effect is maintained 24 h following the final nitrate dose when plasma nitrite levels have returned to baseline. In addition, acute dietary nitrate was recently reported to enhance peak power production. Our purpose was to examine whether chronic dietary nitrate supplementation enhanced peak power 24 h following the final dose and if this impacted performance in a heavily power-dependent sport. METHODS: In a double-blind, randomized, crossover design, maximal aerobic capacity, body composition, strength, maximal power (30 s Wingate), endurance (2 km rowing time trial), and CrossFit performance (Grace protocol) were assessed before and after six days of supplementation with nitrate (NO) (8 mmol·potassium nitrate·d-1) or a non-caloric placebo (PL). A 10-day washout period divided treatment conditions. Paired t-tests were utilized to assess changes over time and to compare changes between treatments. RESULTS: Peak Wingate power increased significantly over time with NO (889.17 ± 179.69 W to 948.08 ± 186.80 W; p = 0.01) but not PL (898.08 ± 183.24 W to 905.00 ± 157.23 W; p = 0.75). However, CrossFit performance was unchanged, and there were no changes in any other performance parameters. CONCLUSION: Consuming dietary nitrate in the potassium nitrate salt form improved peak power during a Wingate test, but did not improve elements of strength or endurance in male CrossFit athletes.

Changes in Body Composition in Division I Football Players Over a Competitive Season and Recovery in Off-Season.

This study investigated changes in body composition over 1 competitive football season in D-I collegiate football players (N = 53; by position, 21 linemen vs. 32 nonline; or by seniority, 30 upperclassmen vs. 23 underclassmen) and additional changes by the following spring season (N = 46; 20 linemen vs. 26 nonline; 27 upperclassmen vs. 19 underclassmen). Body composition by dual-energy x-ray absorptiometry (DXA) was completed pre- and post-season and the following spring. For the team as a whole, player weight decreased 1.3 kg (1.2%) and lean mass decreased 1.4 kg (1.6%) over the season. Absolute fat mass showed no change; however, percent body fat showed a 0.5% increase. There was an interaction between player position and seniority for changes in lean mass (p < 0.01). In nonline positions upperclassmen lost more lean mass than underclassmen, whereas in line positions underclassmen lost more lean mass than upperclassmen. Spring measures indicate that weight did not increase during the off-season, but improvement in body composition was noted. Lean mass increased by 2.2 kg (2.6%), whereas absolute fat mass decreased by 1.4 kg (6.7%). Although weight and lean mass losses during the competitive season were recovered in the off-season, changes in collegiate football programs that include nutrition counseling, dietary recommendations, monitoring of weight, and skin-fold testing as an estimate of body fat change would be beneficial to players. Strength and conditioning coaches and staff need to consider strategies to incorporate these practices into their programs.

Time-to-Fatigue During Incline Treadmill Running: Implications for Individualized Training Prescription.

Uphill running has been touted as a key interval training tactic for distance runners despite few scientifically derived recommendations for individualized training prescription. To date, a majority of uphill training research has focused on shorter, faster training bouts; however, longer, slower bouts based on an individual's velocity at maximum oxygen consumption (Vmax) may prove more effective. One potential longer bout length may be associated with the time Vmax can be maintained (Tmax), an approach proven effective in level-grade interval training. Therefore, the purpose of this investigation included examining the Tmax, heart rate, and test-retest reliability of incline treadmill running (INC) on a 10% grade at 65, 70, 75, 80, and 85%Vmax compared with level-grade running at Vmax. Twelve moderately trained distance runners (age, 26.4 ± 4.8; body mass, 64.3 ± 12.9 kg; height, 171.2 ± 9.3 cm; and V̇O2max, 56.6 ± 7.6 ml·min⁻¹·kg⁻¹) completed 2 Tmax INC trials at each submaximal Vmax and a level-grade Tmax at Vmax. The dependent variables were Tmax, heart rate plateau (HR(Plateau)), and half-time to heart rate plateau (½HR(Plateau)) of each condition. Statistical significance was set to p ≤ 0.05. Student's t-test revealed no significant differences in Tmax, HR(Plateau), and ½HR(Plateau) between trials 1 and 2 at any INC condition. One-way analysis of variance revealed significant differences in (a) Tmax during INC at 75, 80, and 85%Vmax and level-grade at Vmax and (b) ½HR(Plateau) during INC at 80 and 85%Vmax and all other conditions. In conclusion, Tmax and heart rate dynamics during INC proved reliable, and simple regression analysis revealed ∼68%Vmax during INC yields the same level-grade Tmax at Vmax.

The effects of incline and level-grade high-intensity interval treadmill training on running economy and muscle power in well-trained distance runners.

Despite a paucity of evidence, uphill running has been touted as a sport-specific resistance-to-movement training tactic capable of enhancing metabolic, muscular, and neuromuscular processes in distance runners in ways similar to previously established resistance-to-movement training methods, such as heavy and/or explosive strength training and plyometric training. Therefore, the purpose of this investigation included documenting the effects of incline and level-grade interval treadmill training on indices of running economy (RE) (i.e., oxygen consumption [VO2] and blood lactate [BLa] responses of submaximal running) and muscle power. Thirty-two well-trained distance runners (age, 27.4 ± 3.8 years; body mass, 64.8 ± 8.9 kg; height, 173.6 ± 6.4 cm; and VO2max, 60.9 ± 8.5 ml·min(-1)·kg(-1)) received assignment to an uphill (GHill = 12), level-grade (GFlat = 12), or control (GCon = 8) group. GHill and GFlat completed 12 interval and 12 continuous run sessions over 6 weeks, whereas GCon maintained their normal training. Dependent variables measured before and after training were VO2 and BLa at 2 separate velocities associated with lactate threshold (VLT) (VO2-60% and VO2-80%; and BLa-60% and BLa-80%, respectively); percentage of VO2max at lactate threshold (%VO2max at VLT); muscle power as assessed through a horizontal 5-jump test (5Jmax); and isokinetic knee extension and flexion at 3 angular velocities (90, 180, and 300°·s(-1)). Statistical significance was set to p ≤ 0.05. All groups significantly improved 5Jmax, VO2-60%, VO2-80%, BLa-60%, and BLa-80%. Additionally, GHill and GFlat significantly improved %VO2max at VLT. Other indices of RE and muscle power did not improve. We conclude incline treadmill training effective for improving the components of RE, but insufficient as a resistance-to-movement exercise for enhancing muscle power output.

The effects of uphill vs. level-grade high-intensity interval training on VO2max, Vmax, V(LT), and Tmax in well-trained distance runners.

Uphill running represents a frequently used and often prescribed training tactic in the development of competitive distance runners but remains largely uninvestigated and unsubstantiated as a training modality. The purpose of this investigation included documenting the effects of uphill interval training compared with level-grade interval training on maximal oxygen consumption (VO2max), the running speed associated with VO2max (Vmax), the running speed associated with lactate threshold (V(LT)), and the duration for which Vmax can be sustained (Tmax) in well-trained distance runners. Thirty-two well-trained distance runners (age, 27.4 ± 3.8 years; body mass, 64.8 ± 8.9 kg; height, 173.6 ± 6.4 cm; and VO2max, 60.9 ± 8.5 ml·min(-1)·kg(-1)) received assignment to an uphill interval training group (G(Hill) = 12), level-grade interval training group (G(Flat) = 12), or control group (G(Con) = 8). G(Hill) and G(Flat) completed 12 interval and 12 continuous running sessions over 6 weeks, whereas G(Con) maintained their normal training routine. Pre- and posttest measures of VO2max, Vmax, V(LT), and Tmax were used to assess performance. A 3 × 2 repeated measures analysis of variance was performed for each dependent variable and revealed a significant difference in Tmax in both G(Hill) and G(Flat) (p < 0.05). With regard to running performance, the results indicate that both uphill and level-grade interval training can induce significant improvements in a run-to-exhaustion test in well-trained runners at the speed associated with VO2max but that traditional level-grade training produces greater gains.

Osteogenic index and changes in bone markers during a jump training program: a pilot study.

PURPOSE: This study was designed as a proof-of-concept study to assess the osteogenic index (OI) and changes in bone markers during an 8-wk jump training program. On the basis of the OI, jumps were completed in one or two daily sessions with total jumps per day being equal. METHODS: Seven males served as controls and participated in their normal strength training program. Fourteen males were divided into two groups, jumping once daily (J1x) or jumping twice daily (J2x), with a 6-h recovery period between sessions (J2x only). Jumping-type exercises were performed on a Plyo Press and started at 20 plyo-jumps per day, three times per week and progressed to 60 plyo-jumps per day, three times per week for the last 3 wk. Blood samples were collected at baseline and at 4 and 8 wk to determine serum concentrations of bone-specific alkaline phosphate and C-terminal telopeptides of type I collagen. RESULTS: OI for each session and week were different (P < 0.05) between the two jumping groups (baseline OI per week, J1x = 28 +/- 0.9, J2x = 34 +/- 0.9). There was a significant change (P = 0.005) in bone-specific alkaline phosphate over time, with 8-wk values being significantly higher than baseline values (change from baseline: J1x = 2.7 +/- 1.4 microg.L-1, J2x = 3.5 +/- 1.3 microg.L-1). J2x had an overall mean change significantly different from zero. C-terminal telopeptides of type I collagen did not change significantly during the 8 wk. CONCLUSIONS: The data demonstrate that the bone of young adult males does respond to a high-impact exercise. In addition, compared with completing all plyo-jumps in one session, the use of recovery periods between exercise sessions on the same day may result in positive changes in bone turnover, indicative of an osteogenic effect. The beneficial impact of the OI and how it can be used to design programs to influence bone turnover still remain to be determined.

Moderate protein intake improves total and regional body composition and insulin sensitivity in overweight adults.

A high protein intake (approximately 40% of energy intake) combined with aerobic and resistance exercise training is more closely associated with improved body composition and cardiovascular risk profile than a traditional protein intake (approximately 15% of intake) combined with moderate-intensity aerobic exercise. However, there is concern that such high-protein diets may adversely affect health. We therefore tested the hypothesis that moderate protein intake (approximately 25% of energy intake) would elicit similar benefits on body composition and metabolic profile as high protein intake. Twenty-four overweight/obese men and women (body mass index [BMI] = 32.2 +/- 3.4, percentage of body fat [%BF] = 37.3 +/- 8.0) were matched for BMI and %BF and randomly assigned to one of 3 groups for a 3-month nutrition/exercise training intervention: (1) high-protein diet (approximately 40% of energy intake) and combined high-intensity resistance and cardiovascular training (HPEx, n = 8, 5 female and 3 male), (2) moderate-protein diet (approximately 25% of energy intake) and combined high-intensity resistance and cardiovascular training (MPEx, n = 8, 5 female and 3 male), or (3) high-protein diet only (HPNx, n = 8, 5 female and 3 male). Total and regional body composition (dual-energy x-ray absorptiometry), insulin sensitivity (insulin sensitivity index to the oral glucose tolerance test), insulin-like growth factor-1 (IGF-1), IGF binding protein-1 (IGFBP-1), IGF binding protein-3 (IGFBP-3), and blood lipids were measured at baseline and after the intervention. All groups experienced significant (P < .05) and similar losses of body weight, BMI, and total and abdominal %BF, and similar improvements in insulin sensitivity (HPEx, 6.3 +/- 1.2 vs 9.5 +/- 0.98; MPEx, 6.2 +/- 1.4 vs 8.4 +/- 1.6; HPNx, 3.7 +/- 1.1 vs 7.0 +/- 1.1; insulin sensitivity index to the oral glucose tolerance test; P < .05) and leptin levels. Furthermore, the HPEx group demonstrated decreases in total cholesterol (TC) and triglycerides, and increases in IGF-1 and IGFBP-1. The MPEx group experienced decreases in TC, whereas the HPNx group had increases in high-density lipoprotein cholesterol, TC to high-density lipoprotein, IGF-1, and IGFBP-1. In conclusion, moderate protein intake elicits similar benefits in body composition and insulin sensitivity as a high-protein diet. These findings may have practical implications for individuals interested in diets containing elevated dietary protein.

The impact of varying dietary protein on serum IGF-I, IGFBP-1, and IGFBP-3 during 6 days of physical activity.

This study was designed to investigate the impact of dietary protein intake on serum concentrations of IGF-I and IGFBP-1 and relative amounts of serum IGFBP-3 during 6 d of physical activity. Ten men (23.8 +/- 2.0 y of age) were assigned to 1 of 3 trials in a random crossover design. Each trial was isocaloric but with varying amounts of dietary protein: 50 g, 100 g, or 200 g. Subjects expended 500 kcal through treadmill running or weightlifting on alternate days for 6 d. Fasting blood samples were obtained for measurement of IGF-I, IGFBP-1, and IGFBP-3. Pre-post 24-h urine was measured for urea nitrogen. 50 g/d of protein resulted in a negative nitrogen balance, whereas 100 g/d and 200 g/d resulted in a positive nitrogen balance--200 g greater (P < 0.05) than 50 g and 100 g. Baseline IGF-I, BP-1, and BP-3 were not different among treatments. IGF-I decreased (P = 0.002) during the 6 d. Postintervention IGFBP-I was greater (P = 0.03) than at baseline. Postintervention IGFBP-3 values were not different from baseline or between trials. A 6-d modification of protein intake, while in energy balance, during a strength and conditioning program does not appear to modify serum concentrations of IGF-I or IGFBP-1 or relative amounts of IGFBP-3.

Naringin does not alter caffeine pharmacokinetics, energy expenditure, or cardiovascular haemodynamics in humans following caffeine consumption.

1. Naringin, a grapefruit constituent interacts with many medications including caffeine, a popular weight loss supplement. The purpose of the current study was to identify changes in caffeine pharmacokinetics, resting energy expenditure (REE), oxygen consumption (VO(2)) and respiratory exchange ratio (RER) after an acute dosage of caffeine and naringin. 2. Using a double-blinded, counterbalanced design, REE, VO(2), and RER were measured before and systematically for 8 h after a single dosage of caffeine (CAF, 200 mg) with and without naringin (100 mg (CN100) or 200 mg (CN200)) in 10 apparently healthy individuals. A standardized meal was provided following 240-minute measurements (400 kcals; 35 g carbohydrate; 27 g protein; 7 g fat). 3. Caffeine, CN100, CN200 did not alter VO(2) or VO(2) area under the curve (137 301 +/- 8318, 139 729 +/- 9300, 134 297 +/- 8318, mL/480 min). Resting energy expenditure (k/cals) was 10.0 +/- 1.4% higher with CAF versus CN200 (6.0 +/- 1.4%) and CN100 (6 +/- 1.5%) at 240 min (P = 0.07) which was then negated following a standardized meal. Percent change in RER from pre to 240 min and pre to 480 min was not different between the CAF, CN100, or CN200 (-0.2 +/- 1.7%, 1.7 +/- 1.7%, -2.8 +/- 1.9%). 4. Although caffeine alone suggests a trend of increased REE, the results of the present study indicate that concurrent consumption of caffeine with naringin in acute dosages does not affect RER, VO(2), and prevents the increase of REE in adult humans. The results suggest that the interaction of grapefruit juice and caffeine may be due to constituents of grapefruit juice other than naringin or in addition to naringin.

Effect of protein supplementation during a 6-month strength and conditioning program on areal and volumetric bone parameters.

BACKGROUND: Skeletal loading and proper nutrition are necessary for optimal bone health. The appropriate amount of dietary protein to maximize skeletal health, however, is under constant debate. OBJECTIVE: To determine if 6 months of protein supplementation in conjunction with a strength and conditioning training program improves areal and volumetric bone mineral density (BMD). DESIGN: Fifty-two apparently healthy males and females ages 18-25 years were randomized to protein supplement (PRO, Myoplex, EAS, Inc. Golden CO) containing 280 kcal, 42 g protein, 21 g carbohydrate, and 1.5 g fat) or calorically equivalent carbohydrate control (CS). All subjects participated in a 5 sessions/week strength and conditioning program. Volumetric and areal BMD measurements were made by peripheral quantitative computed tomography (pQCT) of the tibia and whole body DXA. pSSI a measure of torsional bone strength, based on structural and material properties was obtained by pQCT. RESULTS: Measurements at the 20% tibia by pQCT revealed that overall there were significant increases in cortical vBMD (4.3 +/- 1.3 mg/cm(3)), cortical area (1.9 +/- 0.6 cm(2)), cortical thickness (0.05 +/- 0.02 mm) and pSSI (67 +/- 24 mm(3)), and a decrease in endosteal circumference (- 0.5 +/- 0.2 mm) over the intervention period (all, P < 0.05). None of the changes in DXA measures were found to differ by group or sex, there was a trend for a greater increase in whole body BMC among the carbohydrate compared to protein supplemented group and a greater increase among males (16 +/- 8 g) compared to females (-9 +/- 9 g) (P = 0.06). CONCLUSIONS: The results of this study indicate that the consumption of additional protein does not improve measurements of vBMD or bone size during a 6-month strength and conditioning program. Longer duration studies may be necessary to determine the influence of increased dietary protein on bone in young adults. Males and females may have different bone responses to increased protein intake while participating in a strength and conditioning program.

Effect of protein supplementation during a 6-mo strength and conditioning program on insulin-like growth factor I and markers of bone turnover in young adults.

BACKGROUND: Exercise is beneficial for bone when adequate nutrition is provided. The role of protein consumption in bone health, however, is controversial. OBJECTIVE: The objective was to ascertain the effect of high protein intake on insulin-like growth factor I (IGF-I) and markers of bone turnover during 6 mo of exercise training. DESIGN: Fifty-one subjects aged 18-25 y (28 men, 23 women) received a protein supplement (42 g protein, 24 g carbohydrate, 2 g fat) or a carbohydrate supplement (70 g carbohydrate) twice daily. Exercise consisted of alternating resistance training and running 5 times/wk. Plasma concentrations of IGF-I, insulin-like growth factor-binding protein 3, serum bone alkaline phosphatase, and urinary N-telopeptide collagen crosslink (NTx) concentrations were measured at 0, 3, and 6 mo after 24 h without exercise and a 12-h fast. RESULTS: Three-day diet records indicated no difference in energy intake between the groups. Average protein intakes after supplementation began in the protein and carbohydrate groups were 2.2 +/- 0.1 and 1.1 +/- 0.1 g/kg, respectively (P < 0.001). The increase in plasma IGF-I was greater in the protein group than in the carbohydrate group (time x supplement interaction, P = 0.01). There were no significant changes over time or significant differences by supplement in plasma insulin-like growth factor-binding protein 3 (44 and 40 kDa). Serum bone alkaline phosphatase increased significantly over time (P = 0.04) and tended to be higher in the protein group than in the carbohydrate group (P = 0.06). NTx concentrations changed over time (time and time squared; P < 0.01 for both) and were greater in the protein group than in the carbohydrate group (P = 0.04). Men had higher NTx concentrations than did women (74.6 +/- 3.4 and 60.0 +/- 3.8 nmol/mmol creatinine; P = 0.005). CONCLUSION: Protein supplementation during a strength and conditioning program resulted in changes in IGF-I concentrations.

Caffeine-herbal ephedra combination increases resting energy expenditure, heart rate and blood pressure.

1. The purpose of the present study was to determine whether the consumption of an acute dose of caffeine and Ma Huang increases resting energy expenditure (REE), heart rate (HR) and blood pressure (BP) over a 3 h period. 2. A randomized, double-blind cross-over study was performed evaluating the acute effects of caffeine (150 mg)/herbal ephedra (Ma Huang; 20 mg ephedra alkaloids) versus a placebo. A total of eight healthy subjects (four males and four females) with a mean (+/-SD) age of 23.4+/-0.8 years (mean ages for males and females: 25.3+/-0.7 and 22.0+/-0.7 years, respectively) and 22.5+/-3.1% body fat (15.7+/-1.2 and 27.6+/-3.5% body fat for males and females, respectively) were recruited to the study. Participants were moderate caffeine users (approximately 150-300 mg/day). 3. Subjects reported to the laboratory following a 12 h fast and 48 h of a caffeine-free diet. Resting energy expenditure was measured prior to supplementation and for 15 min every 30 min for 3 h following supplementation. Heart rate and BP were obtained every 15 min. Blood samples were obtained every 30 min following the measurement of REE and analysed for caffeine, ephedrine, free fatty acids and glucose. 4. By 3 h, HR was 22.7+/-5.5% higher (P<0.05) than baseline for the caffeine/ephedra trial compared with 8.9+/-2.2% higher for the placebo group. At 3 h, systolic BP was 9.1+/-2.2% higher (P<0.05) than baseline for the caffeine/ephedra trial compared with only 1.9+/-2.9% different from baseline for the placebo trial. There was no effect of the caffeine/ephedra combination on diastolic BP. Resting energy expenditure during the last 30 min was 4.5+/-2.5% higher in the placebo trial and 10.7+/-2.5% higher (P<0.05) in the caffeine/ephedra trial; REE was 8.5 +/- 2.0% higher (P<0.05) in the caffeine/ephedra trial compared with the placebo trial. Free fatty acids increased over time in the placebo and caffeine/ephedra trials (from 0.5+/-0.05 to 0.63+/-0.05 mEq/L and from 0.48+/-0.06L to 0.8+/-0.05 mEq/L, respectively). 5. Caffeine and herbal ephedra, at doses of 150 mg and 20 mg (ephedrine), respectively, result in a significant elevation in REE, HR and BP. Although significant, the increase in energy expenditure is negligible in terms of weight loss.