Abstract: Objectives: Predictors of work-related injuries were assessed using data from a group of recruits in the Hellenic Army Academy in Greece. Methods: Participants were 253 recruits who were monitored by physicians for musculoskeletal injuries resulting through a 7-week Basic Combat Training (BCT) period. Potential predictors of musculoskeletal injuries [Cadetsâ entry number, Body Mass Index (BMI), body fat percentage (BFP), gender, age, sport experience (SE) and Greek nationality (GN)] were modelled via univariate and multivariate logistic regressions. Results: Using Odds ratio (OR) and Confidence Interval (CI) it was shown that older age (OR=0.73; 95% CI=0.56-0.96), female gender (OR=0.13; 95% CI=0.02-0.81), high BFP (OR = 1.21; 95% CI = 1.07-1.37), and GN (OR=0.22; 95% CI=0.07-0.69) were all associated with musculoskeletal injuries. These factors, except for gender, were also related to overuse injuries. Conclusions: During BCT adiposity expressed as BFP and not as BMI, can predict the magnitude and type (acute-overuse) of musculoskeletal injuries in Greek recruits.
Abstract: Twenty males [10 fasting (FC) and 10 non-fasting (NFC) cadets] who carried out Hellenic Army Academyâs scheduled training, performed a 2 mile run test (2MRT)] pre and post the Ramadan period. Body mass in FC was significantly decreased (from 76.0±5.8 kg to 74.3±5.7 kg; p<0.05). The magnitude of improvement in 2MRT performance was also greater in FC compared to NFC (2.9% versus 1.6%; p<0.05). No significant differences existed among groups regarding heart rates. In contrast, significant differences (P<0.05) existed for FC who presented higher protein (141.1±3 4.6 g versus 121.8±28.0 g), fat (166.3±3 6.6 g versus 141.4±33.5 g) and lower carbohydrate (369.6±92.0 g versus 458.9±127.6 g) consumption compared to their previous values before fasting. However, no values reported below the Reference Nutrient Intake across all cadets. This study suggests that Ramadan fasting does not lead to nutritional deficiencies or/and performance impairment in a group of Army officer cadets.
Abstract: Objectives: The present study examined various kinematic parameters during walking and running between military boots (MB) used by the Cypriot/Greek Army (without and with commercial insoles and standard running shoes (RS). Methods: Cadence (CA) and step length (SL) were measured using a h/p/Cosmos Gaitway treadmill equipped with two Kistler in-dwelling force plates. Seven participants performed 4-min walks (5kmâ¢h-1) and runs (10kmâ¢h-1) at a 5% gradient under all three conditions [MB, MB + insoles (MBI), RS]. Results: Significant differences existed in SL (p<0.05) and CA during walking between the MBI and the RS. Conclusions: This study suggests that the addition of extra weight (MB) on a participantâs foot had no detrimental effects on velocity characteristics during uphill walking and running. In addition, MBI instead of RS for walking facilitates longer steps at a lower cadence, something that could lead to a more efficient walking during long distance marches.
Abstract: This study assessed the effect of incorrect calculation of power output measurement on the ergogenic properties of creatine. Fifteen males performed repeated Wingate anaerobic tests, under baseline, placebo, and creatine conditions. Statistics showed significant differences (p < 0.05) following creatine-supplemented conditions compared with placebo conditions, whereas no significant differences existed between the baseline and placebo conditions. However, the performance enhancement effect of creatine became significant only when the corrected (for the inertia of the flywheel) method was employed for measuring peak and minimum power. Mean (+/- SD) values across all cycle sprints for placebo versus creatine were 1033 +/- 100 W versus 1130 +/- 95 W for peak power and 385 +/- 78 W versus 427 +/- 70 W for minimum power. No significant differences were shown using the uncorrected method for peak power (756 +/- 97 W versus 786 +/- 88 W) and minimum power 440 +/- 64 W pre versus 452 +/- 65 W post). In conclusion, the present study suggests that the potentiating effect of creatine might be underestimated if the inertial effects of the flywheel are not considered in power output determination.
Abstract: Purpose: This study assessed the effect of acute creatine monohydrate (CR) loading on Creatine Phosphate (CrP), Adenosine Triphosphate (ATP), Lactate (La), Mean Power (MP), Minimum Power (MIP) and Mean Pedal Rate (MPR) during three 30 s Wingate tests (WinT).
Methods: Seven male active subjects had a muscle biopsy at rest and after the 3rd WinT pre and post 25g of Cr for 4 days.
Results: ATP and CrP concentrations after the 3rd WinT were significantly (p<0.05) higher pre vs. post Cr (12.0 ï± 1.1 vs 16.0 ï± 3.2 and 10.3 ï± 1.4 vs 13.2 ï± 5.1 mmol/kg of dry muscle respectively). Performance was also improved significantly (p<0.05) following Cr supplementation, where MP, MIP and MPR were 598 ï± 65 vs 649 ï± 62 Watts, 382 ï± 51 vs 424 ï± 46 Watts and 108 ï± 10 vs 115 ï± 9 rev/m, respectively. Performance improvement became greater at the 3rd WinT with mean percentage improvement being 6.3%, 6.7% and 10.0% for the 1st, 2nd and 3rd WinT respectively.
Conclusions: The present CR regimen significantly increased muscle ATP and CrP, did not alter blood lactate, and led to significantly improved performance especially towards the end of the exercise protocol, possibly via an accelerated ATP and CrP re-synthesis during the recovery period between bouts.
Abstract: The addition of carbohydrate (CHO) to an acute creatine (Cr) loading regimen has been shown to increase muscle total creatine content significantly beyond that achieved through creatine loading alone. However, the potential ergogenic effects of combined Cr and CHO loading have not been assessed. The purpose of this study was to compare swimming performance, assessed as mean swimming velocity over repeated maximal intervals, in high-performance swimmers before and after an acute loading regimen of either creatine alone (Cr) or combined creatine and carbohydrate (Cr + CHO). Ten swimmers (mean +/- SD of age and body mass: 17.8 +/- 1.8 years and 72.3 +/- 6.8 kg, respectively) of international caliber were recruited and were randomized to 1 of 2 groups. Each swimmer ingested five 5 g doses of creatine for 4 days, with the Cr + CHO group also ingesting approximately 100 g of simple CHO 30 minutes after each dose of creatine. Performance was measured on 5 separate occasions: twice at "baseline" (prior to intervention, to assess the repeatability of the performance test), within 48 hours after intervention, and then 2 and 4 weeks later. All subjects swam faster after either dietary loading regimen (p < 0.01, both regimens); however, there was no difference in the extent of improvement of performance between groups. In addition, all swimmers continued to produce faster swim times for up to 4 weeks after intervention. Our findings suggest that no performance advantage was gained from the addition of carbohydrate to a creatine-loading regimen in these high-caliber swimmers.
Abstract: Purpose: The purpose of the present study was to examine the importance of various physiological indices related to the Onset of Blood Lactate Accumulation (OBLA) on predicting 10 kilometer (10km) running performance.
Methods: Seventeen endurance trained males 28-51 years old tested twice, on two separate occasions on a treadmill with a continuous method for the determination of maximum oxygen uptake (VO2max) and OBLA respectively. The determination of OBLA was based on the fixed blood lactate concentration of 4 milimoles per liter (4mmol/l). During testing, except blood during lactate measurements, heart rate and oxygen consumption were also measured.
Results: Mean ± (SD) values for treadmill speed, oxygen consumption, heart rate and percentage of VO2max that correspond to OBLA level, were 16.7 ± 1.9 km/h, 53.0 ± 7.1 ml/kg/min, 167 ± 9.9 b/min and 80.1 ± 7.6 % respectively. Treadmill speed and oxygen consumption at OBLA level showed strong correlation (r=-0.87 and r=-0.84 respectively; p<0.001) with 10km performance but there was only a moderate relationship (r=-054; p<0.05) for OBLA expressed % of VO2max.
Conclusions: The results of the present study suggest that the faster 10km performance times were best explained by higher treadmill speed and oxygen consumption at OBLA level rather than the percentage of VO2max associated with the mentioned intensity.
Abstract: The aim of the present study is to investigate Urinary creatine (URCR) and urinary creatinine (URCRN) response to CR supplementation in conjunction with exercise performance.
Abstract: Purpose: This study aimed to determine the effects of different acute creatine loadings (ACRL) on repeated cycle sprints.
Methods: Twenty eight active subjects divided into the control (n=7) and the experimental (n=21) group. The exercise protocol comprised three 30s Anaerobic Wingate Tests (AWT) interspersed with six minutes recovery, without any supplements ingested and following placebo and creatine ingestion, according to each ACRL (40g, 100g and 135g throughout a four-day period). Blood and urinary creatine levels were also determined from the experimental group for each ACRL. Protein intake (across all groups) was held constant during the study. Results: There were no changes in protein intake or performance of the control group. For the experimental group creatine supplementation produced significant (paired t-test ) increases in body mass (82.5 ± 1.4kg pre vs 82.9 ± 1.2kg post., p<0.01), blood (0.21 ± 0.04mmol l-1 pre vs 2.24 ± 0.98mmol l-1 post., p<0.01), and urinary (0.23 ± 0.09mmol l-1 pre vs 4.29 ± 1.98mmol l-1 post., p<0.01), creatine. No significant differences were found between the non-supplement and placebo condition. Creatine supplementation produced an average improvement of 0.7%, 11.8% and 11.1% for the 40g, 100g and 135g ACRL respectively. However, statistics (two-way ANOVA repeated measures) revealed significant differences (p<0.01) only for the 100g and 135g ACRL. Mean ± SD values (Watts) for the 100g ACRL for mean and minimum power were 612 ± 180 placebo vs 693 ± 221 creatine and 381 ± 35 placebo vs 415 ± 11 creatine accordingly. For the 135g ACRL the respective performance values were 722 ± 215 placebo vs 810 ± 240 creatine and 405 ± 59 placebo vs 436 ± 30 creatine.
Conclusions: These data indicate that a 100g compared to 40g ACRL produces a greater potentiation of performance whilst, greater quantities of creatine ingestion (135g ACRL) can not provide a greater benefit.
Abstract: Purpose: The purpose of the present study was to develop a standardised testing procedure in order to obtain reproducible peak anaerobic power values prior to a 30 s Anaerobic Wingate Test (AWT).
Methods: The experimental group (n=30) consisted of sedentary (S), active individuals (A), and club level athletes participating in multiple sprint events (football, rugby, sprint cycling) (M.S.) with mean age 22.4 + 4.3 years, body mass 80.1 + 1.3 kg, height 1.81 + 0.9 m and % body fat 16.4 + 5.1. The first week of tests comprised a series of six to eight 6 s cycle sprint and the second week, one 30 s cycle sprint. Statistics (ANOVA with repeated measures) showed significant differences (P<0.01) between the lowest and the highest peak power values for the 6 s series, which implies a learning effect during cycle sprinting.
Results: Mean + SD values for the highest vs lowest peak power were 1148 ï± 83 vs 998 ï± 117 1584 ï± 280 vs 1459 ï± 302 and 1297 ï± 127 vs 1066 ï± 137 for the S, M.S. and P.E. group respectively. Additionally, the present data showed that both the S and A group produced their highest peak power output after a minimum number of six 6 s cycle sprints. In contrast, the M.S. group required less familiarisation (four 6 s cycle sprints). in cycle sprinting, possibly due to regular participation in multiple sprint events.
Conclusions: In conclusion, when testing sedentary, active or athletic populations a series of 6 s cycle sprints is necessary to establish reproducible peak anaerobic power values before proceeding to the 30 s AWT. A minimum number of four trials are sufficient for athletes participating in multiple sprint events, compared to a minimum number of six trials for sedentary and active individuals.
Abstract: We investigated the effect of an acute creatine loading (25 g per day for 4 days) and longer-term creatine supplementation (5 g of creatine or 5 g of placebo per day for 2 months) on the performance of 22 elite swimmers during maximal interval sessions. After the acute creatine loading, the mean of the average interval swim times for all swimmers (n = 22) improved (44.3+/-16.5 s before vs. 43.7+/-16.3 s after supplementation; P<0.01). Three of the 22 swimmers did not respond positively to supplementation. After 2 months of longer-term creatine supplementation or placebo, neither group showed a significant change in swimming performance (38.7+/-13.5 s before vs. 38.7+/-14.1 s after for the creatine group; 48.7+/-18.0 s before vs. 48.7+/-18.1 s after for the placebo group). We conclude that, in elite swimmers, 4 days of acute creatine loading improves swimming performance significantly when assessed by maximal interval sessions. However, longer-term supplementation for 2 months (5 g of creatine per day) did not benefit significantly the creatine group compared with the placebo group.
Abstract: Purpose: The purpose of this study was to investigate the relationship between 10 km running performance and VO2max as measured by a continuous horizontal treadmill test performed to volitional exhaustion.
Methods: Ten male athletes (mean age 32.6 8.6 years, mass 67.8 ± 9.1 kg, height 1.74 ± 0.05 m and 10 km time 36.1 ± 2.5 min) participated in the present study. Mean ± (SD) values of the major variables were as follows: 62.7 ± 4.2 ml kg-1 min-1, 4.23 ± 0.5 l min-1, Peak Treadmill Speed (PTS) 19.9 ± 2 km h-1, Heart rate 183 ± 8.5 beats min-1, Lactate 8.8 ± 2.9 mmoles-1.
Results: The results demonstrated no significant correlation between 10 km time and VO2max (ml kg-1 min-1) r=0.49 and r=0.50 respectively (p>0.05). Four subjects failed to satisfy the criteria of VO2max (McConnell, 1987) but presented the best 10 km times and the lowest blood lactates associated with PTS. Peak Treadmill Speed was also correlated with both 10 km running times (r=-0.81) and 10 km race pace (r=0.76) (p<0.05). Although VO2max was very reproducible (Coefficient of variation 1.82%) it was not an accurate predictor of 10 km performance for the present sample group. However, the use of a horizontal treadmill protocol for the determination of VO2max should be considered because provides specific information about the subjects; training adaptations as reflected in PTS.
Conclusions: Although VO2max is considered a prerequisite for elite endurance performance, does not necessarily determine success in a homogenous group of 10 km runners.
Abstract: Experiment 1
Given the lack of evidence regarding optimum creatine dosages, the effects of three different creatine dosages (10g, 25g and 35g of creatine monohydrate day-1 for 4 days) on various AWT indices were investigated using 28 males, 7 for each dosage and 7 controls. All AWT indices (except fatigue index) increased significantly (ANOVA; P<0.01) (mean 14%) following creatine supplementation. Performance potentiation progressively increased with subsequent AWTs. No significant differences were found between baseline and placebo condition. The 25g dosage produced a greater improvement of performance compared to the 10g dosage (20.1 and 4.4% respectively). No further improvement was found with the use of the 35g dosage (18.5%). These findings support the literature which suggests that dosages of the order of 20g. day-1 for 5 days or 25g. day-1 for 4 days will promote muscle creatine uptake and enhance anaerobic performance.
Experiment 2
Based on the above experiment the effects of two 4 day supplementations with 25g of creatine monohydrate per day (separated by 4 months) on the performance of 21 elite swimmers (7 experimental and 14 as control swimmers) were investigated. Following both creatine supplementations there was a significant (P<0.05) improvement in interval swimming times (Friedman and Wilcoxon) as measured against their placebo and baseline times respectively. Race times also increased significantly (P<0.05) for both supplementation periods. No significant differences were found for the control swimmers. These data suggest that creatine ingestion enhances elite swimming performance and these beneficial effects can be repeated four months later.
Experiment 3
Using muscle biopsy procedures experiment 3 sought to investigate the effects of 25g of creatine monohydrate for 4 days on various muscle metabolites during 3 AWTs. TCr was significantly (Wilcoxon; P<0.05) increased in the eight subjects following supplementation and was strongly related to performance potentiation (r= 0.64 to 0.83; P<0.01). ATP and CP concentrations were decreased less in each AWT following supplementation. In AWT3 ATP and CP concentrations were 12% and 28% (P<0.05) higher than the respective baseline values. The mechanisms responsible for the improved performance following creatine supplementation were suggested to be a higher CP content pre exercise, an increased muscle buffering capacity and an increased capacity for CP resynthesis. The present results showed that creatine supplementation facilitates ATP production by an increased CP resynthesis and/or by an accelerated reduction in hydrogen ion concentration.
