Effects of explosive type strength training on physical performance characteristics in cross-country skiers

Summary To investigate the effects of a combination of simultaneous strength and endurance training on selected neuromuscular and aerobic performance characteristics seven male cross-country skiers underwent training for a period of 6 weeks. The experimental group trained 6–9 times per week with a programme consisting of 34% explosive type strength training and 66% endurance training during the first 3 weeks of the experiment and 42% and 58% respectively during the last 3 weeks of the experiment. The total volume of training of the control group (eight skiers) was of the same magnitude but consisted of 85% pure endurance training and 15% endurance type strength training. The experimental training regime resulted in specific changes in neuromuscular performance. This was demonstrated by improvements (P<0.01) in the maximal heights of rise of the centre of gravity in the squat and countermovement jumps. A significant decrease (P<0.05) took place also in the time of rapid isometric force production during experimental training, while no changes occurred in the maximal force of the trained muscles. Aerobic performance characteristics of the experimental group did not change during the experimental training period. No significant changes occurred in neuromuscular or aerobic performance characteristics in the control group. These findings indicated that training-induced improvements in explosive force production may not be fully inhibited by this kind of aerobic training. They also suggested that endurance athletes could undertake explosive type strength training programmes without a concomitant reduction in aerobic capacity, if the overall loading of training were within predefined limits.     

Changes in fitness and shipboard task performance following circuit weight training programs featuring continuous or interval running

Summary Pre- and post-physiological data were collected on 57 Navy men (¯x age=19.5 years) who participated in either circuit weight training/ continuous run (CWT/CR) (N=31) or circuit weight training/interval run (CWT/IR) (N=26) programs. Measured variables included 4 measures of upper torso dynamic strength (one repetition maximum [1RM] for arm curl, bench press, shoulder press, and lat pull-down); two measures of lower torso dynamic strength (1RM) for knee extension and leg press); one measure of power (number of revolutions completed on an arm ergometer (Monark^®) at maximum drag); three measures of muscular endurance (number of repetitions at 60% 1RM for bench press and leg press and maximal number of bent-knee sit-ups in 120 s); one stamina measure (time to exhaustion on a cycle ergometer (Monark^®) maximal work capacity [MWC] test; and three simulated shipboard tasks: manikin shoulder drag, open/secure a water tight door and paint bucket carry. Composite shipboard performance derived from the summed time (s) required to complete the three tasks was also calculated. Results show performance on the manikin shoulder drag and majority of evaluative fitness measures was significantly (p<0.05) enhanced following both circuit weight training/run formats. Significantly (p<0.05) higher values for shoulder press (F=7.2), arm ergometer (F=5.3), and sit-ups (F=6.8) and lower values for leg press muscular endurance (F=5.1) were observed in CWT/IR when compared to CWT/CR. Regression analysis yielded the following prediction equation: Composite shipboard performance (s)=194.15097-1.59492 (arm curl) -0.18369 (leg press)r=0.74.It can be concluded that exercise participation was associated with differential changes in fitness but not job performance. Furthermore, the association between fitness gains and job criteria performance appeared to be specific to the task modelled. Important predictors of criterion task performance included parameters of upper torso and lower torso muscular strength.Report No. 85-33 was supported by the Naval Medical Research and Development Command, Department of the Navy, under research Work Unit M0096-PN.001-1050. The views presented in this paper are those of the authors. No endorsement by the Department of the Navy has been given or should be inferred     

Glenohumeral rotational motion and strength and baseball pitching biomechanics

Context:

Addressing loss of shoulder range of motion and rotator cuff weakness in injury-prevention programs might be an effective strategy for preventing throwing arm injuries in baseball pitchers. However, the influence of these clinical measures on pitching biomechanics is unclear.

Objective:

To evaluate the relationships among clinical measures of shoulder rotational motion and strength and 3-dimensional pitching biomechanics and to evaluate the presence of coupling between the shoulder and the elbow during pitching to provide insight into the influence of clinical shoulder characteristics on elbow biomechanics.

Design:

Cross-sectional study.

Setting:

Biomechanics laboratory.

Patients or Other Participants:

A total of 27 uninjured male high school baseball pitchers (age  =  16 ± 1.1 years, height  =  183 ± 7 cm, mass  =  83 ± 12 kg).

Main Outcome Measure(s):

Clinical measures included shoulder internal- and external-rotation range of motion and peak isometric internal- and external-rotator strength. Three-dimensional upper extremity biomechanics were assessed as participants threw from an indoor pitching mound to a target at regulation distance. Linear regressions were used to assess the influence of clinical measures on the peak shoulder internal and external rotation moments and the peak elbow-adduction moment.

Results:

We found a positive relationship between clinically measured internal-rotator strength and shoulder external-rotation moment (R²  =  0.181, P  =  .04) during pitching. We also noted an inverse relationship between clinically measured external-rotation motion and the elbow-adduction moment (R²  =  0.160, P  =  .04) and shoulder internal-rotation moment (R²  =  0.250, P  =  .008) during pitching. We found a positive relationship between peak shoulder internal-rotation moment and the peak elbow-adduction moment (R²  =  0.815, P < .001) during pitching.

Conclusions:

This study provides insight into the effects of shoulder strength and motion on pitching biomechanics and how these clinical measures might contribute to throwing arm injuries in the baseball pitcher. A relationship also was identified between peak shoulder and elbow moments in the throwing arm during pitching, providing biomechanical support for addressing clinical shoulder characteristics as a potential strategy for preventing elbow injury.     

Effects of endurance training on left ventricular performance: a study in anaesthetized rabbits

Endurance training is known to increase ventricular performance during exercise and to decrease resting heart rate. The aim of this study was to evaluate a model for endurance training in rabbits and to study the effects of endurance training on local myocardial performance in the left ventricle during resting conditions. One group of rabbits underwent a 10-week exercise training programme. The rabbits trained 5 days a week on a treadmill. Training periods increased gradually from 15 min to 1 h with increments in speed from 0.5 to 1.2 km h¹. After the training programme the rabbits were anaesthetized and studied as acute open-chest preparations. A micro-tip pressure transducer was introduced via apex to the left ventricle and two pairs of ultrasonic crystals were implanted in the left anterior wall to measure segment lengths. One pair measured shortening in the circumferential direction whereas the other pair measured shortening in the longitudinal direction. Heart rate was lower in the trained group (n = 5), 172 + 9 beats min“‘ (mean±SEM), compared with 235 ± 19 beats min ’ in the control group (n = 8) (P < 0.02). Stroke volume, measured by radio-nuclidelabelled microspheres, was greater in the trained rabbits compared with controls (P < 0.03). Shortening in both segments was of similar magnitude for the trained and control groups. End-systolic pressure-length relations (ESPLR) obtained by occlusion of the descending aorta (balloon catheter) showed reduced slopes for longitudinal segments in the trained group compared with the control group (P < 0.05). We conclude that this endurance training programme in rabbits can be used to study myocardial effects of endurance training. Furthermore, the less steep slope of ESPLRs for the longitudinal segment in the trained animals might indicate a structural myocardial remodelling and increased contractile reserve that might be recruited during adrenergic stimulation in the trained group.     

基因多态性与杰出运动能力

背景：人的运动能力具有很高的遗传度,随着分子生物学技术和检测方法的发展,体育科研工作者越来越关心基因的变化对优秀运动员运动能力的影响,也逐渐认识到通过基因来预测杰出运动能力的重要价值。 目的：对当前基因多态性与杰出运动能力关联研究领域的研究发现和成果进行全面的综述,并对这些研究的共性问题进行阐述,给出今后发展的可能建议。 方法：计算机检索PubMed数据库以及中国期刊网全文数据库1998至2013年期间有关杰出运动能力与基因多态性方面的文章。分别以“Elite athlete performance”、“Gene polymorphism”、 “Endurance”、“Power”、“Training response”为关键词进行检索,最初检索到150篇中英文文献,最后根据内容纳入80篇文献。 结果与结论：当前研究杰出运动能力与基因多态性主要集中在杰出耐力素质、杰出爆发力素质和运动训练敏感性3个方面与基因多态性的关联上。杰出耐力素质相关基因主要有ACE、线粒体DNA、PPAR、ADR、GNB3、NRF2等基因;杰出爆发力素质相关基因主要有ACTN3、ACE、GDF-8、IL-6、HIF-1等基因;与运动训练敏感性相关的基因主要有HBB、TFAM、NRF2、AR、FECH等基因。近年来杰出运动能力相关基因多态性的研究大量出现,但仍存在着一些不足,如样本量较小、研究对象涉及人种较为单一等。将众多研究得到的理论成果可以通过建立某些算法和模型应用到运动员基因选材中。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

The reproducibility of an endurance performance test in adolescent cyclists

The purpose of the study was to measure the reproducibility of a performance test in well-trained adolescent cyclists. Eight male and one female cyclist [mean age 15.7 (0.7) y] participated in the study. Lactate threshold (LT) and peak VO₂ were assessed. The performance test was repeated on three separate days and consisted of 30 min of steady state (SS) cycling at 80% of individual LT. Immediately after the SS cycling a time trial (TT) started with the cyclists having to complete a fixed amount of work as fast as possible. Reliability was assessed for the TT with the coefficient of variation (CV) as the (SD/mean)*100 for each participant, intraclass correlation coefficients (ICC) and typical error (SD of the difference in mean /2). The group mean (SD) times for the TT were TT1 1889 (306), TT2 1857 (283) and TT3 1953 (279) s respectively. Individual CV varied from 0.25% to 10%. The ICC for TT1/2 and 2/3 were r=0.78 and 0.93 (P<0.05). The typical errors, expressed as a CV% on the log transformed performance times, were 7.3 and 3.7% for TT1/2 and TT2/3 respectively. The largest individual CVs were observed between TT1 and TT2. The differences in CV and SD among the three TTs indicate that trial two and three were more reliable than TT1, suggesting a habituation trial is needed. It is concluded that the present performance test is reliable in adolescent cyclists with lower variation between trials 2 and 3.     

Muscular adaptations to computer‐guided strength training with eccentric overload

Aims: In order to investigate the muscular adaptations to a novel form of strength training, 18 male untrained subjects performed 4 weeks of low resistance–high repetition knee extension exercise. Methods: Nine of them trained on a conventional weight resistance device (Leg curler, CON/ECC group), with loads equivalent to 30% of the concentric one‐repetition maximum (1RM) for both the concentric and eccentric phase of movement. The other nine trained on a newly developed computer‐driven device (CON/ECC‐OVERLOAD group) with the concentric load equivalent to 30% of the concentric 1RM and the eccentric load equivalent to 30% of the eccentric 1RM. Results: Training resulted in significantly (P ≤ 0.05) increased peak torque and a tendency (P = 0.092) to increased muscle cross‐sectional area for the CON/ECC‐OVERLOAD but not the CON/ECC group, while strength endurance capacity was significantly (P ≤ 0.05) increased in the CON/ECC group only. RT‐PCR revealed significantly increased myosin heavy chain (MHC) IIa and lactate dehydrogenase (LDH) A mRNAs, a tendency for increased MHC IIx mRNA (P = 0.056) and high correlations between the changes in MHC IIx and LDH A mRNAs (r = 0.97, P = 0.001) in the CON/ECC‐OVERLOAD group. Conclusions: These results indicate a shift towards a more type II dominated gene expression pattern in the vasti laterales muscles of the CON/ECC‐OVERLOAD group in response to training. We suggest that the increased eccentric load in the CON/ECC‐OVERLOAD training leads to distinct adaptations towards a stronger, faster muscle.     

Creatine supplementation enhances maximum voluntary isometric force and endurance capacity in resistance trained men

The present study examined the hypothesis that creatine (Cr) supplementation can increase the performance of isometric exercise in subjects engaged in a strength training program. Ten male subjects were tested in three experimental trials 7 days apart (days 1, 8 and 15). In each trial the subjects' maximum voluntary force of contraction (MVC) was measured in both legs and isometric endurance capacity at 80, 60, 40 and 20% of MVC of their stronger leg (knee extensor group) was measured with a 4-min rest between contractions. Additionally, the subjects' isometric endurance capacity at 80% of MVC of their weaker leg was measured in 10 repeated bouts interspersed with 2-min rest. A double-blind cross-over design was adopted for administering Cr or placebo. Subjects were randomized into either the Cr–placebo (Group A: days 2–6: 10 g day^?1 of Cr; days 9–13: 10 g day^?1 of glucose polymers) or the placebo–Cr group (Group B reverse supplementation order). The daily diet was analysed, and urine samples from 24-h collections were subjected to Cr and creatinine analysis. In each subject, ≈18 g (35%) of Cr was eliminated in the urine during the Cr supplementation period. MVC increased by about 10% (P < 0.01 in the weaker leg, P < 0.05 in the stronger leg) and body mass increased by 1.7 ± 0.4 kg (2.3%, P < 0.01) and 1.8 ± 0.3 kg (2.1%, P < 0.01) in groups A and B, respectively, after Cr supplementation, while energy intake and diet composition remained constant throughout the study. The subjects' endurance capacity increased (P < 0.05) in all the bouts after Cr supplementation. Muscle hypertrophy in response to Cr supplementation and weight training may explain the findings of the present study.     

Indicators of maximal hiking performance in Laser sailors

Laser class sailors have to hike out, i.e. hook their feet under the toe straps near the centreline of the boat and hold their upper bodies over the edge of the boat, to counteract the heeling forces generated by the sails. To identify the parameters that are associated with maximal hiking performance, this cross-sectional observational study measures various knee extensor and hip flexor muscle performance characteristics in 55 Laser sailors and correlates each with the area-under-the-curve hiking moment over 3 min of hiking on a hiking dynamometer (HM₁₈₀). Our results showed that higher body mass and HM₁₈₀ were significantly associated with better race scores (Spearman’s rho = − 0.69 and − 0.62, respectively, both P < 0.01) in male sailors who participated in the National Inter-School Laser competition. Body mass (Pearson’s correlation coefficient, r ≥ 0.95, P < 0.01 in both males and females), maximum voluntary isometric strength of the quadriceps (r ≥ 0.80, P < 0.01 in both males and females), and 3-RM knee extension strength (r ≥ 0.80, P < 0.01 in both males and females) were associated with a higher HM₁₈₀. The correlations between height, abdominal muscle endurance (crunches), explosive lower body strength (vertical jumps), cycling time-to-exhaustion, quadriceps strength endurance, or isometric quadriceps endurance with incremental loads (bucket test), and HM₁₈₀ were weaker (r < 0.60). HM₁₈₀ may be a useful performance indicator for Laser racing. Since strength measures correlated well with HM₁₈₀, greater emphasis should be placed on developing maximum strength in the quadriceps to improve maximal hiking performance.     

Neuromuscular and hormonal responses in elite athletes to two successive strength training sessions in one day

Summary Acute neuromuscular and endocrine adaptations to weight-lifting were investigated during two successive high intensity training sessions in the same day. Both the morning (I) (from 9.00 to 11.00 hours) and the afternoon (II) (from 15.00 hours to 17.00 hours) training sessions resulted in decreases in maximal isometric strength (p<0.01 and <0.05), shifts (worsening) in the force-time curve in the absolute scale (p<0.05 and ns.) and in decreases in the maximal integrated EMG (p<0.01 and <0.05) of the selected leg extensor muscles. Increases in serum total (p<0.05) and free testosterone (p<0.01) and in cortisol (p<0.01) concentrations were found during training session II. These were followed by decreases (p<0.001 andp<0.01 and ns.) in the levels of these hormones one hour after the termination of the session. The responses during the morning training session were different with regard to the decreases in serum total testosterone (p<0.05), free testosterone (ns.) and cortisol (p<0.05). Only slight changes were observed in the levels of luteinizing hormone and sex hormone-binding globulin during the training sessions. Increases (p<0.01) took place in somatotropin during both training sessions. The present findings suggest that high intensity strengthening exercises may result in acute adaptive responses in both the neuromuscular and endocrine systems. The diurnal variations may, however, partly mask the exercise-induced acute endocrinological adaptations in the morning. Recording of muscle activation and muscle strength and analysis of certain serum hormone concentrations with sufficient frequency during the training process may be useful in optimizing and controlling the contents of individual training sessions and the full training program.     

Hormonal responses to training and its tapering off in competitive swimmers: relationships with performance

During a winter training season, the effects of 12 weeks of intense training and 4 weeks of tapering off (taper) on plasma hormone concentrations and competition performance were investigated in a group of highly trained swimmers (n = 8). Blood samples were collected and the swimmers performed their speciality in competition at weeks 10 (mid-season), 22 (pre-taper) and 26 (post-taper). No statistically significant changes were observed in the concentrations of total testosterone (TT), non-sex hormone binding globulin-boundtestosterone (NSBT), cortisol (C), luteinising hormone, thyroid stimulating hormone, triiodothyronine, thyroxine plasma catecholamines, creatine kinase and ammonia during training and taper. Mid-season NSBT: C ratio and the amount of training were statistically related (r = 0.82,P < 0.05). Competition performance slightly declined during intense training [0.52 (SD 2.51) %, NS] and improved during taper [2.32 (SD 1.69)%,P < 0.01]. Changes in performance during training and taper correlated with changes in ratios TT: C (r = 0.86,P < 0.01andr = 0.81,P < 0.05, respectively) and NSBT: C (r = 0.77,P < 0.05 andr = 0.76,P < 0.05, respectively). In summary, these results showed that the monitored plasma hormones and metabolic indices were unaltered by 12 weeks of intense training and 4 weeks of taper. The TT: C and NSBT: C ratios, however, appeared to be effective markers of the swimmers' performance capacities throughout the training season.     

Muscle training in muscular dystrophies

There has been a debate for many years on whether muscular training is beneficial or harmful for patients with myopathic disorders and the role of exercise training in the management of these patients is still controversial. Much of this confusion is because of the lack of well‐designed controlled training studies on this heterogenic group of disorders. Because effective therapies are still lacking, the patients have to rely on symptomatic treatment in which continuous physiotherapy plays an important role. There is thus still a need for studies evaluating the short‐ and long‐term effects of muscular training in different types of myopathic disorders. We need to elucidate whether muscular training can increase strength and resistance to fatigue, but most importantly, we need to clarify whether training can improve specific functional abilities of the patient with myopathy. Future studies should give us specific information on what type of training, endurance or strength training, is to be preferred for different myopathies. The effect of strength training in one type of muscle disorder is not directly applicable to another, but is largely dependent on the underlying biological defect. From the studies published so far, high‐resistance strength training at submaximal and possibly also at near‐maximal levels seem beneficial, at least in the short perspective for slowly progressive myopathic disorders. However, the long‐term effects of such training have not been systematically studied. In rapidly progressive myopathies, which are caused by deficient structural proteins such as in Duchenne’s muscular dystrophy, the use of high‐resistance training is far more controversial and questionable. If exercise regimens are to be used, they should preferably commence in the early stages of the disease, at which time there is still a substantial amount of trainable muscle fibres.     

Dietary intervention and training in swimmers

Summary To ascertain if muscle damage occurred in swimmers as a result of high-intensity training and to find if fluid and dietary manipulation could affect muscle damage, we studied 40 members of the University of Florida swimming team using creatine kinase (CK) and lactic dehydrogenase (LDH) as markers of muscle damage during a 6-month period of intensive training. During this time, training intensity, fluid intake during exercise and dietary supplementation were all modified one by one to examine their individual effects. During a control period of 4 weeks, all swimmers drank water before and during (120 min) workouts. CK in men at the end of this period averaged 315, SD 122 (normal < 170 IU · l^–1). Half of the swimmers were then given 500 ml of a glucose-electrolyte solution (GES) (Na 21 mmol · l^–1, Cl 13 mmol · l^–1, K 2.5 mmol · l^–1, PO₄ 5 mmol · l^–1 and glucose 6%) before workouts and twice at intervals during the workout, while half continued to drink the same volume of water. One week after division into fluid groups, the workout intensity was increased by about 10%. Another week later CK had increased to 500, SD 180 IU · l^–1 in swimmers drinking water, but fell to 280, SD 105 IU · l^–1 in those drinking GES (P < 0.05). The second phase of the study began after a 4-week control period during which all athletes drank water before and during workouts. The swimmers were divided into four matched groups. Group I drank water before and during workouts and 250 ml of a 16% sucrose solution after; group II drank water before and during exercise and 250 ml of a milk protein supplement (MPS) containing 15 g lactalbumin and 16% sugar afterwards; group III drank GES before and during and the sucrose drink after exercise; group IV drank GES before and during and the MPS drink after exercise. Then during a 6-week period, the intensity of exercise was progressively increased by 25%. CK increased 61% (P < 0.01) in group I men, while it fell 12% (P < 0.05) in groups II and III, and 41% (P < 0.01) in group IV. In women, CK in group I increased 18% (P < 0.05); in group II it decreased 3.5%, in group III was unchanged, and in group IV declined 12.6% (P < 0.05). The final phase of the study was performed on 8 olympic swimmers who performed identical workouts each Saturday for 4 weeks. The 1st week they ingested water before and during exercise and the 16% sucrose solution afterwards. The 2nd week the GES solution was consumed before and during exercise and the sucrose solution afterwards. The 3rd week water was consumed before and during and MPS afterward and the 4th week GES before and during and MPS afterwards. Determination of CK and LDH before, immediately after, and at intervals afterwards showed that CK and LDH increased less when GES was the test fluid during exercise than when water was consumed. Recovery, as judged by return of CK and LDH to control values was more rapid when MPS was the post-exercise fluid than when the sucrose solution was given.     

Benefits of caffeine ingestion on sprint performance in trained and untrained swimmers

Summary The influence of specific training on benefits from caffeine (Caf) ingestion was examined during a sprint test in a group of highly trained swimmers (T) and compared with the response of a group of untrained occasional swimmers (UT). Seven T and seven UT subjects swam freestyle two randomly assigned 2 × 100 m distances, at maximal speed and separated by 20 min of passive recovery, once after Caf (250 mg) and once after placebo (Pla) ingestion. Anaerobic capacity was assessed by the mean velocity (meters per second) during each 100 m and blood was sampled from the fingertip just before and 1, 3, 5, 7, and 9 min after each 100 m for resting and maximal blood lactate concentration ([1a^–]_{b, max}) determination. The [[1a^–]_{b, max} was significantly enhanced by Caf in both T and UT subjects (P<0.01). However, only T subjects exhibited significant improvement in their swimming velocity (P<0.01) after Caf or any significant impairment during the second 100 m. In light of these results, it appears that specific training is necessary to benefit from the metabolic adaptations induced by Caf during supramaximal exercise requiring a high anaerobic capacity.     

Effect of intense swimming training on rhinitis in high‐level competitive swimmers

Background Rhinitis is commonly reported by swimmers. Seasonal allergic rhinitis may impair athletes' performance and quality of life (QOL). No data are currently available on the changes of nasal symptoms during and after a swimming season. We aimed to determine in competitive swimmers: (1) the prevalence of rhinitis and its impact on their QOL during an intense training programme, (2) the changes in nasal symptoms and QOL after a resting period and (3) the relationship between rhinitis and airway hyperresponsiveness (AHR). Methods Thirty‐nine swimmers and 30 healthy controls answered the Rhinitis Quality of Life Questionnaire (RQLQ) and scored nasal symptoms on a seven‐point Likert scale during the week preceding their visit. Subjects had allergy skin prick tests and a methacholine challenge. Peak nasal inspiratory flows were also measured. The athletes performed these tests during an intense training period (V1), outside the pollen season and after at least 2 weeks without swimming (V2). Results At V1, rhinitis symptoms were reported by 74% of swimmers and 40% of controls (P<0.01). Eighty‐four percent of swimmers and 72% of controls were atopic (NS). RQLQ score was higher in swimmers compared with controls at V1 (27.3 ± 28.5 vs. 9.5 ± 12.7, respectively, P<0.005). The presence of AHR during training did not correlate with the presence of rhinitis symptoms. At V2, the nasal symptoms and RQLQ scores were similar in swimmers and controls. Conclusion Intense swimming training is associated with an increase in nasal symptoms and impairment in QOL in most competitive swimmers. Such an increase is not related to seasonal allergen exposure in atopic athletes and probably results from chlorine derivative exposure. Cite this as: V. Bougault, J. Turmel and L. P. Boulet, Clinical & Experimental Allergy, 2010 (40) 1238–1246.     

Influence of altitude training modality on performance and total haemoglobin mass in elite swimmers

We compared changes in performance and total haemoglobin mass (tHb) of elite swimmers in the weeks following either Classic or Live High:Train Low (LHTL) altitude training. Twenty-six elite swimmers (15 male, 11 female, 21.4 ± 2.7 years; mean ± SD) were divided into two groups for 3 weeks of either Classic or LHTL altitude training. Swimming performances over 100 or 200 m were assessed before altitude, then 1, 7, 14 and 28 days after returning to sea-level. Total haemoglobin mass was measured twice before altitude, then 1 and 14 days after return to sea-level. Changes in swimming performance in the first week after Classic and LHTL were compared against those of Race Control (n = 11), a group of elite swimmers who did not complete altitude training. In addition, a season-long comparison of swimming performance between altitude and non-altitude groups was undertaken to compare the progression of performances over the course of a competitive season. Regardless of altitude training modality, swimming performances were substantially slower 1 day (Classic 1.4 ± 1.3% and LHTL 1.6 ± 1.6%; mean ± 90% confidence limits) and 7 days (0.9 ± 1.0% and 1.9 ± 1.1%) after altitude compared to Race Control. In both groups, performances 14 and 28 days after altitude were not different from pre-altitude. The season-long comparison indicated that no clear advantage was obtained by swimmers who completed altitude training. Both Classic and LHTL elicited ~4% increases in tHb. Although altitude training induced erythropoeisis, this physiological adaptation did not transfer directly into improved competitive performance in elite swimmers.     

Effects of ischaemic training on local aerobic muscle performance in man

The aim of the study was to compare the effects of ischaemic and non-ischaemic training on aerobic performance. In 10 subjects, peak oxygen uptake (peak V_{O 2}) and time to fatigue (TTF) for one-legged exercise were measured before and after 4 weeks (4 times week-1) of one-legged training. Each training session started with one leg training for 45 min with 20% blood-flow reduction induced by local application of a supra-atmospheric external pressure of 50 mmHg (ischaemic leg; I-leg). We have previously shown that this decreases leg blood flow by about 20%. The contralateral leg (nonrestricted-flow leg; N-leg), serving as a control, then trained with an identical power-output profile for 45 min but without flow restriction. In the I-leg the average training-induced increments in TTF and peak V_{O 2} were 27 and 24%, respectively. In the N-trained leg TTF and peak-V_{O 2} increased 10 and 14%, respectively. Both increments were significantly greater (P < 0.05) in the I-trained leg. Moreover, the performance increase in the I-trained leg was exaggerated (P < 0.05) in the ischaemic test condition, i.e. there was a specificity in the training response. In conclusion, ischaemia acts as an additive stimulus to training leading to an exaggerated increase in endurance and peak-V_O2 compared to identical training without blood-flow restriction. The main explanation is probably an enhanced local adaptation in the I-trained leg.