Development and Maintenance of Sprint Training Adaptations: An Uphill-Downhill Study.

ABSTRACT: Bissas, A, Paradisis, GP, Nicholson, G, Walker, J, Hanley, B, Havenetidis, K, and Cooke, CB. Development and maintenance of sprint training adaptations: an uphill-downhill study. J Strength Cond Res 36(1): 90-98, 2022-We examined the development of performance adaptations resulting from an uphill-downhill training program and monitored the decline of adaptations during detraining. Twenty-eight men were randomly assigned to 1 of 2 sprint training groups who trained 3 times per week for 6 weeks and a control group (C). The uphill-downhill group (U+D) trained on an 80-m platform with 3° slopes, whereas the horizontal (H) group trained on flat track. Subjects were tested for maximal running speed (MRS), associated kinematics, and leg strength before and after training, with U+D subjects also tested after weeks 2 and 4 of training, and after a 3-week detraining period. The U+D group increased their MRS by 3.7% (from 8.75 ± 0.72 to 9.07 ± 0.64 m·s-1, p < 0.05), their stride rate by 3.1% (from 4.21 ± 0.21 to 4.34 ± 0.18 Hz, p < 0.05), and their knee extensors' maximum isometric force by 21% (from 2,242 ± 489 to 2,712 ± 498 N, p < 0.05) after training. The time course of changes showed declines for weeks 1-4 (1.4-5.1%), but an ascending trend of improvement compensated all losses by the end of week 6 (p < 0.05). During detraining, no decreases occurred. No changes were observed for the H and C groups. The minimum period to produce positive effects was 6 weeks, with a very good standard of performance maintained 3 weeks after training. U+D training will prove useful for all athletes requiring fast adaptations, and it can fit into training mesocycles because of its low time demands.

Muscle-tendon morphology and function following long-term exposure to repeated and strenuous mechanical loading.

We mapped structural and functional characteristics of muscle-tendon units in a population exposed to very long-term routine overloading. Twenty-eight military academy cadets (age = 21.00 ± 1.1 years; height = 176.1 ± 4.8 cm; mass = 73.8 ± 7.0 kg) exposed for over 24 months to repetitive overloading were profiled via ultrasonography with a senior subgroup of them (n = 11; age = 21.4 ± 1.0 years; height = 176.5 ± 4.8 cm; mass = 71.4 ± 6.6 kg) also tested while walking and marching on a treadmill. A group of eleven ethnicity- and age-matched civilians (age = 21.6 ± 0.7 years; height = 176.8 ± 4.3 cm; mass = 74.6 ± 5.6 kg) was also profiled and tested. Cadets and civilians exhibited similar morphology (muscle and tendon thickness and cross-sectional area, pennation angle, fascicle length) in 26 out of 29 sites including the Achilles tendon. However, patellar tendon thickness along the entire tendon was greater (P < .05) by a mean of 16% for the senior cadets compared with civilians. Dynamically, cadets showed significantly smaller ranges of fascicle length change and lower shortening velocity in medial gastrocnemius during walking (44.0% and 47.6%, P < .05-.01) and marching (27.5% and 34.3%, P < .05-.01) than civilians. Furthermore, cadets showed lower normalized soleus electrical activity during walking (22.7%, P < .05) and marching (27.0%, P < .05). Therefore, 24-36 months of continuous overloading, primarily occurring under aerobic conditions, leads to more efficient neural and mechanical behavior in the triceps surae complex, without any major macroscopic alterations in key anatomical structures.

Prognostic potential of body composition indices in detecting risk of musculoskeletal injury in army officer cadet profiles.

OBJECTIVES: High values in most of the body composition indices have been related to musculoskeletal injuries, but limited data exists on the accuracy of these diagnoses when detecting musculoskeletal injuries in military populations. METHODS: The suitability of body fat percentage, body mass index, fat mass index and fat free mass index to identify injury risk was examined in a group of army officer recruits. All body composition diagnoses were measured in 268 male army officer recruits prior to the commencement of basic combat training. Musculoskeletal injury was identified using codes from the International Classification of Diseases. The area under the curve, in the receiver operating characteristic curve, was used to quantify the overall ability to discriminate between those who were injured and those who were not. RESULTS: The statistics indicated that all indices, apart from body mass index, had a significant possibility to detect musculoskeletal injury potential (p < 0.05; 61%-63%). The respective cut-off points used to classify individuals as injured were for body fat percentage >22, for fat mass index >6.5 and for fat free mass index <16.5. CONCLUSION: Body mass index values can not similarly detect the possibility of occurrence of musculoskeletal injuries in army officer recruits, just as other body composition diagnoses related to fat mass or/and free fat mass. However, the cut off-points related to the overall diagnostic performance of each body composition index should be used with caution and in accordance with the aims of each experimental setting.

The use of creatine supplements in the military.

INTRODUCTION: Creatine is considered an effective nutritional ergogenic aid to enhance exercise performance. In spite of the publication of several reviews in the last decade on the topic of exercise performance/sports and creatine there is a need for an update related to the military given the lack of information in this area. The aim of this study was to critically assess original research addressing the use of creatine supplements in the military. METHODS: A search of the electronic databases PubMed and SPORTDiscus, for the following key words: military personnel, trainees, recruit, soldier, physical fitness, physical conditioning, creatine supplementation, creatine ingestion, nutritional supplements to identify surveys and randomised clinical trials from journal articles and technical reports investigating the effect of creatine supplementation on military populations. RESULTS: Thirty-three out of 90 articles examined the use of creatine as a dietary supplement in military personnel. Twenty-one studies were finally selected on the basis of stated inclusion criteria for military surveys and randomised clinical trials. Most of the surveys (15/17) in the military indicate a high popularity of creatine (average 27%) among supplement users. In contrast, in most of the exercise protocols used (6/9) during randomised clinical trials creatine has produced a non-significant performance-enhancing effect. CONCLUSIONS: Creatine is one of the most widely used supplemental compounds in the military. It is not considered a doping infraction or related to any adverse health effects but its long-term usage needs further investigation. Experimental research suggests that creatine supplementation does not enhance physical performance in the military. However, limitations in creatine dosage, military fitness testing and sample group selection might have underestimated the ergogenic properties of creatine. Recent studies also indicate positive effects on various aspects of total force fitness such as cognitive-psychomotor performance, bone health, musculoskeletal damage and neuromuscular function.

Cadets' swimming and running performance with and without a combat uniform.

INTRODUCTION: The aim was to examine whether a combat uniform (CU) influences the cadet's exercise performance in and out of the water. METHODS: Fourteen male Army Officer cadets performed on 6 separate days: (1) a maximal 400-m freestyle swimming trial; (2) a 4 x 50-m all-out freestyle swimming trial with 10 s rest in between; (3) a 50-m swim obstacle course with a CU (CUs); (4) a 50-m swim obstacle course without a CU (NUs); (5) a 1000-m track run with a CU (CU(R)); and (6) a 1000-m track run without a CU (NUR). In each trial, performance time, oxygen uptake (Vo2), lactate concentration ([La]), and capillary oxygen saturation (SpO2) were recorded. RESULTS: The mean performance time was 44.3 +/- 3.1 s and 33.4 +/- 1.8 s in CUs and NUs trials, respectively. Peak VO2 was similar in CUs, NUs, and 400 m (CUs: 59.1 +/- 1.1 ml x kg(-1) x min(-1), NUs: 57.3 +/- 2.1 ml kg(-1) x min(-1), 400 m: 58.2 +/- 1.6 ml x kg(-1) min(-1)). [La] was higher in CUs than in NUs (CUs: 10.0 +/- 2.0 mmol x L(-1), NUs: 8.5 +/- 1.8 mmol x L(-1)), but it was lower in CUs and NUs than during the 400 m and 4 x 50 m. SpO2 was lower (approximately 4.5%) in CUs than NUs. No differences were observed between running trials. CONCLUSIONS: The results suggest that the use of CU during swimming tasks induces high demands for energy and, thus, leads to a significant impairment of the swimming performance of the cadets. However, the influence of the CU seems to be less crucial during dry land running performance.

Cypriot and greek army military boot cushioning: ground reaction forces and subjective responses.

Lower limb injuries are a continual and serious issue for military personnel. Such injuries have been associated with the requirement to train in military boots (MBs) and might be offset with commercial insoles. In this study, ground reaction forces were measured in seven male participants wearing running shoes (RS), MBs commonly used by Cypriot and Greek Army personnel, and the MBs with two types of shock-absorbing insole. The participants performed 4-min trials at walking pace (5 km·h-1) and running pace (10 km·h-1) at a 5% gradient on a treadmill under all four shod conditions. The treadmill incorporated two force plates under its belt, which provided measurements of key kinetic variables. During walking, RS showed significantly lower values for impact peak force (p < 0.01), maximum force (p < 0.05), and push-off rate (p < 0.05) compared with other conditions, although no significant differences were found during running. Although the RS were rated significantly more comfortable than any other condition, neither insole made the MBs more comfortable to wear. With little evidence to support wholesale adoption of insoles in MBs, their use by military personnel can only be recommended on a case-by-case basis.

Risk factors for musculoskeletal injuries among Greek Army officer cadets undergoing Basic Combat Training.

OBJECTIVES: Predictors of work-related injuries were assessed using data from a group of Greek Army officer cadets. METHODS: Cadets (n = 253) were monitored by physicians for musculoskeletal injuries resulting through a 7-week Basic Combat Training (BCT) period. Potential predictors of musculoskeletal injuries (Cadets' entry number, body mass index [BMI], body fat percentage [BFP], gender, age, sport experience, and nationality) were modeled 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 Greek nationality (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 cadets.

Profiles of musculoskeletal injuries among Greek Army officer cadets during basic combat training.

OBJECTIVE: Injury prevalence and types of injury were recorded among Greek Army officer cadets during basic combat training (BCT). METHODS: Two hundred thirty-three male recruits from the Hellenic Army Academy were monitored for musculoskeletal injuries during a 7-week BCT period. RESULTS: Sixty-six (28.3%) recruits suffered from some form of injury, leading to 1.22 training days lost per study recruit. More than half of the injuries (51.3%) occurred in the first 2 weeks of the BCT, with ankle/foot strains and sprains being the most common injuries. CONCLUSION: Despite the absence of fractures and the low number of upper extremity injuries during the BCT, injury prevalence was high, with ankle- and foot-related injuries to be responsible for a long period of lost training days. Preventive efforts should focus on addressing the high rate of first-time and recurrent ankle ligament sprains and possible protective equipment to limit their frequency and severity.

Effects of acute creatine loading with or without carbohydrate on repeated bouts of maximal swimming in high-performance swimmers.

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.

The use of varying creatine regimens on sprint cycling.

This study aimed to determine the effects of different acute creatine loadings (ACRL) on repeated cycle sprints. 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. There were no changes in protein intake or performance of the control group. For the experimental group creatine supplementation produced significant (p<0.01) increases in body mass (82.5 ± 1.4kg pre vs 82.9 ± 1.2kg post), blood (0.21 ± 0.04mmol·l(-1) pre vs 2.24 ± 0.98mmol·l(-1) post), and urinary creatine (0.23 ± 0.09mmol·l(-1) pre vs 4.29 ± 1.98mmol·l(-1) post). 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 revealed significant (p<0.01) differences only for the 100g and 135g ACRL. Mean ± SD values for the 100g ACRL for mean and minimum power were 612 ± 180W placebo vs 693 ± 221W creatine and 381 ± 35W placebo vs 415 ± 11W creatine accordingly. For the 135g ACRL the respective performance values were 722 ± 215W placebo vs 810 ± 240W creatine and 405 ± 59W placebo vs 436 ± 30W creatine. 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.