Hemostatic effect of tranexamic acid (transamin) during coronary artery bypass grafting

The hemostatic effect of tranexamic acid (TA) was evaluated in patients undergoing coronary artery bypass grafting (CABG). The subjects were 33 serial patients who underwent elective CABG performed by the same team between January 1997 and April 2000. They were divided into a group that received TA (n=15) and a non-TA control group (n=18). The TA group received 50mg/kg of TA intravenously before starting cardiopulmonary bypass (CPB) and 25 mg/kg immediately after CPB. Blood loss from the end of CPB to completion of surgery (post-CPB), as well as during the first 6h (BL6), 6–12 h (BL6–12), 12–18h (BL12–18), and 18–24h after surgery (BL18–24), was compared between the two groups. The time of chest tube removal, the volume of blood transfused, and graft patency were also compared. The blood loss at BL6, BL6–12, BL12–18, and BL18–24, as well as the blood transfussion volume, were all significantly (P<0.05) lower in the TA group than in the control group. There was no significant difference in graft patency between the two groups. In CABG patients, TA reduced blood loss without affecting graft patency, suggesting that it is useful in this setting.     

Effects of taurolidine and octreotide on port site and liver metastasis after laparoscopy in an animal model of pancreatic cancer

Port site metastasis is a dreadful event following laparoscopy; however, the exact pathomechanism is still unknown. In order to prevent trocar metastasis we determined the effects of intraperitoneal lavage with either taurolidine or octreotide on port site and liver metastasis after laparoscopy in a chemically induced, solid pancreatic adenocarcinoma. Pancreatic adenocarcinoma was induced in 60 Syrian hamsters by weekly injection of 10 mg/kg body weight N-nitrosobis-2-oxopropylamine s.c. for 10 weeks. Six weeks later, a laparoscopic pancreatic biopsy was performed by the use of a pneumoperitoneum with carbon dioxide (12 mm Hg), followed by an abdominal irrigation with 5 ml normal saline (group 1, n=20), 5 ml 0.5% taurolidine (group 2, n=20) or 5 ml octreotide (20 mg/ml) (group 3, n=20). After 8 weeks, all hamsters were sacrificed and histopathologically examined. There was only one macroscopic visible primary tumor in the taurolidine group (5.9%), compared to 42.1% in the saline group and 62.5% in the octreotide group (P<0.05). The size of carcinomas was smaller in the saline group than after octreotide irrigation (median 6, range 2–25 vs. median 70, range 40–160 mm², P<0.05). The number of liver metastases per animal was increased after saline irrigation (median 4, range 2–6), compared to taurolidine (median 2, range 1–3) or octreotide (median 2.5, range 2–4) (P<0.05). Port site metastases were found in 36.8% after saline, in 37.5% after octreotide and in 0% after taurolidine irrigation (P<0.05). Thus port site metastasis was effectively prevented by taurolidine irrigation after staging-laparoscopy in pancreatic cancer. This revised version was published online in July 2006 with corrections to the Cover Date.     

Saliva immunoglobulins in elite women rowers

Saliva immunoglobulins (sIgA, sIgG, and sIgM) and upper respiratory tract infection (URTI) rates were evaluated in 20 elite female rowers and 19 nonathletes. Also, the influence of carbohydrate versus placebo beverage consumption on saliva immunoglobulin responses to rowing training sessions was measured in 15 rowers and in 5 non-exercising rowers. Saliva samples were collected 1 day before, and 5–10 min and 1.5 h after rowing or rest. Pre-exercise sIgA (but not sIgG or sIgM) concentration was 77% higher in the rowers compared to nonathletes (P < 0.001). Health records kept over 2 months revealed mean 5.2 (SEM 1.2) and 3.3 (SEM 1.1) days with URTI symptoms for the rowers and controls, respectively. For all 39 subjects, and for the 20 rowers separately, no significant correlation was found between URTI symptoms or insulin, cortisol, and growth hormone concentrations and pre-exercise or exercise-related changes in saliva immunoglobulin concentrations or secretion rates. The patterns of change in saliva immunoglobulin concentration and secretion rate did not differ between the carbohydrate and placebo rowing trials, or between exercised and rested athletes. These data indicated an increased sIgA concentration in the female elite rowers compared to the nonathletes, no association between saliva immunoglobulins and URTI, and no effect of a normal 2-hour training session or carbohydrate ingestion on saliva immunoglobulin concentrations or secretion rates. Accepted: 23 August 1999     

Protein supplementation before and after resistance training in older men

We determined the effects of protein supplementation immediately before (PRO-B) and after (PRO-A) resistance training (RT; 12 weeks) in older men (59–76 years), and whether this reduces deficits in muscle mass and strength compared to younger men (18–40 years). Older men were randomized to PRO-B (0.3 g/kg protein before RT + placebo after RT, n=9), PRO-A (placebo before + protein after RT, n=10), or PLA (placebo before and after RT, n=10). Lean tissue mass, muscle thickness of the elbow, knee, and ankle flexors and extensors, and leg and bench press strength were measured before and after RT and compared to databases of younger subjects (n=22–60). Myofibrillar protein degradation (3-methylhistidine) and bone resorption (cross-linked N-telopeptides) were also measured before and after RT. Lean tissue mass, muscle thickness (except ankle dorsi flexors), and strength increased with training (P<0.05), with little difference between groups. There were no changes in 3-methylhistidine or cross-linked N-telopeptides. Before RT, all measures were lower in the older compared to younger groups (P<0.05), except for elbow extensor muscle thickness. Following training, muscle thickness of the elbow flexors and ankle dorsi flexors and leg press strength were no longer different than the young, and elbow extensor muscle thickness was greater in the old men (P<0.05). Supplementation with protein before or after training has no effect on muscle mass and strength in older men. RT was sufficient to overcome deficits in muscle size of the elbow flexors and ankle dorsi flexors and leg press strength in older compared to younger men.     

Bone metabolism in elite male rowers: adaptation to volume-extended training

We examined the effect of 6-month volume-extended training on bone metabolism in elite male rowers. Twelve elite male rowers (20.8±3.0 years; 192.9±4.7 cm; 91.9±5.3 kg; body fat 10.1±2.3%; 6.2±0.5 l min⁻¹) participated in this study. Bone biochemical markers, hormones, bone mineral content (BMC), and bone mineral density (BMD) were assessed before and after training. Average weekly training volume was significantly higher (P<0.05) during the 6 months of heavy training compared to relative rest (11.6±0.4 h week⁻¹ vs. 16.8±0.6 h week⁻¹), while intensity remained the same. At the end of training, only arm BMD was significantly increased by 5.7%. Osteocalcin (16.6%), insulin-like growth factor-1 (IGF-1) (20.2%) and the bioavailability IGF-1 index (17.9%) were significantly increased. Before heavy training, relationships were observed between the whole body BMD and growth hormone (r=0.64; P≤0.02), lumbar spine BMD and 1.25(OH)₂ vitamin D (r=0.69; P≤0.04), arm BMD and testosterone (r=0.59; P≤0.05), and arm BMD and adiponectin (r=0.59; P≤0.05). No relationship was found between BMC or BMD and blood biochemical measures 6 months later (r=0.56; P≥0.05). In addition, osteocalcin was related to IGF-1 (r>0.58; P<0.048) and bioavailability IGF-1 index (r>0.59; P≤0.055) before and after training. In summary, heavy training had a moderately favorable effect on BMD. Bone tissue at specific skeleton sites is sensitive to changes in training volume even in athletes with already high BMD values. Changes in BMD and bone formation may be caused by changes in specific hormones such as IGF-1 and adiponectin in male athletes.     

The influence of inspiratory and expiratory muscle training upon rowing performance

We investigated the effect of 4 week of inspiratory (IMT) or expiratory muscle training (EMT), as well as the effect of a subsequent 6 week period of combined IMT/EMT on rowing performance in club-level oarsmen. Seventeen male rowers were allocated to either an IMT (n = 10) or EMT (n = 7) group. The groups underwent a 4 week IMT or EMT program; after interim testing, both groups subsequently performed a 6 week program of combined IMT/EMT. Exercise performance and physiological responses to exercise were measured at 4 and 10 week during an incremental rowing ergometer ‘step-test’ and a 6 min all-out (6MAO) effort. Pressure threshold respiratory muscle training was undertaken at the 30 repetition maximum load (∼50% of the peak inspiratory and expiratory mouth pressure, P _Imax or P _Emax, respectively). P _Imax increased during the IMT phase of the training in the IMT group (26%, P < 0.001) and was accompanied by an improvement in mean power during the 6MAO (2.7%, P = 0.015). Despite an increase in P _Emax by the end of the intervention (31%, P = 0.03), the EMT group showed no significant changes in any performance parameters during either the ‘step-test’ or 6MAO. There were no significant changes in breathing pattern or the metabolic response to the 6MAO test in either group, but the IMT group showed a small decrease in HR (2–5%, P = 0.001). We conclude that there were no significant additional changes following combined IMT/EMT. IMT improved rowing performance, but EMT and subsequent combined IMT/EMT did not.     

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.     

Seasonal variation in basal metabolic rates among the yakut (Sakha) of Northeastern Siberia

Objectives: Previous research has shown that indigenous circumpolar populations have elevated basal metabolic rates (BMRs), yet few studies have explored whether metabolic rates increase during the winter. This study addresses this gap by examining seasonal variation in BMR and its associations with thyroid function and lifestyle factors among the Yakut (Sakha) of Siberia. Methods: Anthropometric dimensions, BMR, and thyroid hormone levels (free triiodothyronine [fT3], free thyroxine [fT4], thyroid‐stimulating hormone [TSH]) were measured on two occasions (July/August, 2009 and January 2011) on a sample of 94 Yakut (Sakha) adults (35 men, 59 women) from the rural village of Berdygestiakh, Sakha Republic, Russia. Results: Seasonal changes in BMR varied by age. Younger Yakut adults (19–49 years) showed significant elevations in winter‐time BMR of 6% (P < 0.05), whereas older individuals (≥50 years) showed modest declines (2%; n.s.). Both younger and older Yakut men and women showed increased respiratory quotients during the winter. FT3 and fT4 levels significantly declined during the winter in both younger and older Yakut men and women (P < 0.05). Lifestyle factors were significant predictors of BMR variation, particularly among older men and women. Conclusions: Among the Yakut, increased wintertime BMR was observed among younger but not older adults, whereas all adults showed sharp reductions in free thyroid hormone levels during the winter. Among men, greater participation in subsistence activities was associated with increased BMRs and greater fat oxidation. Among women, variation in food use had the strongest impact on metabolic function. Am. J. Hum. Biol. 26:437–445, 2014. © 2014 Wiley Periodicals, Inc.     

Lipid and lipoprotein profiles, cardiovascular fitness, body composition, and diet during and after resistance, aerobic and combination training in young women

The purpose of this study was to evaluate the effects of various modes of training on the time-course of changes in lipoprotein-lipid profiles in the blood, cardiovascular fitness, and body composition after 16 weeks of training and 6 weeks of detraining in young women. A group of 48 sedentary but healthy women [mean age 20.4 (SD 1) years] were matched and randomly placed into a control group (CG, n=12), an aerobic training group (ATG, n=12), a resistance training group (RTG, n=12), or a cross-training group that combined both aerobic and resistance training (XTG, n=12). The ATG, RTG and XTG trained for 16 weeks and were monitored for changes in blood concentrations of lipoprotein-lipids, cardiovascular fitness, body composition, and dietary composition throughout a 16 week period of training and 6 weeks of detraining. The ATG significantly reduced blood concentrations of triglycerides (TRI) (P < 0.05) and significantly increased blood concentrations of high-density lipoprotein-cholesterol (HDL-C) after 16 weeks of training. The correlation between percentage fat and HDL-C was 0.63 (P < 0.05), which explained 40% of the variation in HDL-C, while the correlation between maximal oxygen uptake (V˙O_2max) and HDL-C was 0.48 (P < 0.05), which explained 23% of the variation in HDL-C. The ATG increased V˙O_2max by 25% (P < 0.001) and decreased percentage body fat by 13% (P < 0.05) after 16 weeks. Each of the alterations in the ATG had disappeared after the 6 week detraining period. The concentration of total cholesterol (TC), TRI, HDL-C and low density lipoprotein-cholesterol in the blood did not change during the study in RTG, XTG and CG. The RTG increased upper and lower body strength by 29% (P < 0.001) and 38%, respectively. The 6 week detraining strength values obtained in RTG were significantly greater than those obtained at baseline. The XTG increased upper and lower body strength by 19% (P < 0.01) and 25% (P < 0.001), respectively. The 6 week detraining strength values obtained in XTG were significantly greater than those obtained at baseline. The RTG, XTG and CG did not demonstrate any significant changes in either V˙O_2max, or body composition during the training and detraining periods. The results of this study suggest that aerobic-type exercise improves lipoprotein-lipid profiles, cardiorespiratory fitness and body composition in healthy, young women, while resistance training significantly improved upper and lower body strength only. Accepted: 9 April 2000     

Basal testicular testosterone production in endurance-trained men is suppressed

Research indicates that endurance-trained men have lower basal testosterone concentrations than age-matched sedentary control men. The physiological cause for this finding is uncertain. Therefore, we examined the peripheral component in the hypothalamic–pituitary–testicular (H–P–T) axis in endurance-trained men to determine if their basal testicular production of testosterone was compromised. The study design was retrospective, with a case-control approach. Age-matched, trained (n=5, TRN) and sedentary control men (n=6, SED) were infused with gonadotrophin-releasing hormone (GnRH) to induce testicular testosterone production via subsequent luteinizing hormone elevations. Testosterone production rate was statistically analyzed with adjustments for confounding factors and compared between groups. The basal testosterone concentrations differed significantly between the TRN and SED groups [pooled mean values; 13.9 (3.0) nmol·l⁻¹ vs 23.4 (3.2) nmol·l⁻¹, P<0.05]. The testosterone production rate was significantly lower (~20–30%; P<0.05) in the TRN men as compared with the SED men following GnRH infusion. It was concluded that the exogenous stimulated testicular production rate of endurance-trained men is suppressed. This finding may account, in part, for the lower circulating basal testosterone concentrations found in these men. The present evidence supports the hypothesis that endurance exercise training induces a degree of peripheral adaptation (i.e., testicle) in the H–P–T axis. Whether this adaptation in the axis is a permanent or transient phenomenon in these men remains to be determined. Electronic Publication     

Contributions of force and velocity to improved power with progressive resistance training in young and older adults

We investigated the effects of age on changes in the force and velocity components of knee extension (KE) power during 16 weeks of traditional progressive resistance training (PRT). Thirty-one young (27 ± 1 years, 16 men, 15 women) and 30 older (64 ± 1 years, 14 men, 16 women) adults trained by KE, leg press, and squat 3 days/week. PRT consisted of three sets with an appropriate load for 8–12 repetitions to fatigue. Testing occurred at baseline, 8, and 16 weeks. Thigh lean mass (TLM) was measured by DEXA. KE load–power and load–velocity curves were generated from peak concentric contractions against loads equivalent to 20, 30, 40, 50, and 60% maximum voluntary isometric contraction (MVC) force. Quadriceps neural activation relative to maximum was assessed during a sit-to-stand task. Participants increased KE 1RM (P < 0.05) by 8 weeks with young adults also increasing strength from 8 to 16 weeks. Adjusting for TLM, all groups increased KE specific strength (P < 0.05). MVC improved by 8 weeks in older adults and by 16 weeks in young subjects (P < 0.05). Neural activation requirements during standing and sitting declined in older adults by 8 weeks (P < 0.05). The KE load–power curve improved for all groups (P < 0.05) by 8 weeks with only young adults improving from 8 to 16 weeks. Peak concentric velocity increased only in older adults (P < 0.05). Training improvements in power resulted primarily from increases in strength both early and late for young adults while older adults realized early improvements in both strength and peak concentric velocity. Grants: This study was supported by National Institute on Aging Grant R01 AG017896 (MMB), Department of Veterans’ Affairs Merit Grant (MMB), and General Clinical Research Center Grant M01 RR00032.     

Effect of concurrent strength and endurance training on skeletal muscle properties and hormone concentrations in humans

The purpose of this study was to investigate the effect of concurrent strength and endurance training on strength, endurance, endocrine status and muscle fibre properties. A total of 45 male and female subjects were randomly assigned to one of four groups; strength training only (S), endurance training only (E), concurrent strength and endurance training (SE), or a control group (C). Groups S and E trained 3 days a week and the SE group trained 6 days a week for 12 weeks. Tests were made before and after 6 and 12 weeks of training. There was a similar increase in maximal oxygen consumption (V˙O_{2 max}) in both groups E and SE (P < 0.05). Leg press and knee extension one repetition maximum (1 RM) was increased in groups S and SE (P < 0.05) but the gains in knee extension 1 RM were greater for group S compared to all other groups (P < 0.05). Types I and II muscle fibre area increased after 6 and 12 weeks of strength training and after 12 weeks of combined training in type II fibres only (P < 0.05). Groups SE and E had an increase in succinate dehydrogenase activity and group E had a decrease in adenosine triphosphatase after 12 weeks of training (P < 0.05). A significant increase in capillary per fibre ratio was noted after 12 weeks of training in group SE. No changes were observed in testosterone, human growth hormone or sex hormone binding globulin concentrations for any group but there was a greater urinary cortisol concentration in the women of group SE and decrease in the men of group E after 12 weeks of training (P < 0.05). These findings would support the contention that combined strength and endurance training can suppress some of the adaptations to strength training and augment some aspects of capillarization in skeletal muscle. Accepted: 10 November 1998     

Adaptation to chronic eccentric exercise in humans: the influence of contraction velocity

We compared changes in muscle fibre composition and muscle strength indices following a 10 week isokinetic resistance training programme consisting of fast (3.14 rad^.s^–1) or slow (0.52 rad^.s^–1) velocity eccentric muscle contractions. A group of 20 non-resistance trained subjects were assigned to a FAST (n=7), SLOW (n=6) or non-training CONTROL (n=7) group. A unilateral training protocol targeted the elbow flexor muscle group and consisted of 24 maximal eccentric isokinetic contractions (four sets of six repetitions) performed three times a week for 10 weeks. Muscle biopsy samples were obtained from the belly of the biceps brachii. Isometric torque and concentric and eccentric torque at 0.52 and 3.14 rad^.s^–1 were examined at 0, 5 and 10 weeks. After 10 weeks, the FAST group demonstrated significant [mean (SEM)] increases in eccentric [29.6 (6.4)%] and concentric torque [27.4 (7.3)%] at 3.14 rad^.s^–1, isometric torque [21.3 (4.3)%] and eccentric torque [25.2 (7.2)%] at 0.52 rad^.s^–1. The percentage of type I fibres in the FAST group decreased from [53.8 (6.6)% to 39.1 (4.4)%] while type IIb fibre percentage increased from [5.8 (1.9)% to 12.9 (3.3)%; P<0.05]. In contrast, the SLOW group did not experience significant changes in muscle fibre type or muscle torque. We conclude that neuromuscular adaptations to eccentric training stimuli may be influenced by differences in the ability to cope with chronic exposure to relatively fast and slow eccentric contraction velocities. Possible mechanisms include greater cumulative damage to contractile tissues or stress induced by slow eccentric muscle contractions. Electronic Publication     

STRONG ASSOCIATION BETWEEN THE RESPONDER STATUS OF THE FCγ II RECEPTOR and RECURRENT SPONTANEOUS ABORTION

Several models exist for the aetiology and therapy of recurrent spontaneous abortion (RSA). They are based in part on the assumption that an increased materno-fetal histocompatibility results in an insufficient maternal immunological recognition of the fetus, and thus renders the maternal immune system unable to sustain the pregnancy. The involvement of the FCγII receptor (FcγIIR) in RSA was suggested, since FcγIIR-blocking antibodies, present in normal pregnancies, could not be found in patients suffering from RSA. The FcγIIR is known to be functionally and structurally dimorphic, which results in a responder, respectively non-responder pattern. We used an in vitro proliferation assay to distinguish between FCγIIR responder and non-responder phenotypes. In 29 RSA couples we found 97% (28/29) of RSA patients and 100% (29/29) of their partners to be responders, whereas 50 fertile couples and a further 100 unrelated controls revealed distributions of responder vs. non-responder of 73% vs. 27% and 70% vs. 30%, respectively. These differences (RSA vs. controls) are highly significant (P≤ 0.0001). Our results suggest further that the FcγIIR dimorphism might be involved in the pathogenesis of RSA.     

Cellulitis Complicating Lymphoedema

 In ten hospitalised patients with cellulitis complicating lymphoedema encountered over a 3-year period (1996–1998), the underlying diseases were carcinoma of the cervix (n=4), uterus (n=1), vagina (n=1), breast (n=2) and nasopharynx (n=1), and retroperitoneal squamous cell carcinoma (n=1). Three of the ten patients had positive blood cultures, compared to none of the 20 age-matched, sex-matched controls hospitalised for cellulitis without lymphoedema. The mean duration of fever, tachycardia and cellulitis was significantly longer in patients with lymphoedema than in those without (P<0.05, P<0.05, and P<0.005 respectively). Early treatment initiated by patients themselves may help stop bacterial replication in the initial stages and minimise further damage to the lymphatic system.     

Influence of prolonged continuous exercise on hormone responses to subsequent exercise in humans

This study examined the possibility that fatigue may modify the hormone responses to exercise. A group of 12 endurance trained athletes ran for 2 h (blood lactate concentrations of approximately 2 mmol·l^–1) in order to induce fatigue. The subjects exercised for 10 min at 70% maximal oxygen uptake before (1st test) and after (2nd test) the 2 h run to assess hormone responsiveness. A 1 min anaerobic power test was performed to assess muscle power. Cortisol, growth hormone, testosterone and insulin concentrations were determined before and after the 1st and 2nd tests. The 1st test resulted in increases in concentrations (P<0.05) of cortisol and growth hormone, a decrease in insulin concentration (P<0.01) and no change in testosterone concentration. The 2 h run caused decreases of insulin, increases of growth hormone concentration and variable responses in the concentrations of cortisol and testosterone. The 2nd test decreased insulin concentration further (P<0.05), but responses of the concentrations of testosterone, growth hormone and cortisol were variable. In 6 subjects (group A) cortisol displayed an increase [mean (SD)] from baseline concentrations [+304.0 (60.0) nmol·l^–1], while in the other 6 subjects (group B) a decrease or no change was seen [+3.1 (5.3) nmol·l^–1 ,between groups, P<0.05]. Growth hormone concentration was substantially higher in group A [+14.7 (4.8) ng·ml^–1] than group B [+6.0 (2.9) ng·ml^–1] following the 2nd test. In group A anaerobic muscle power was higher, while in group B it was lower, after the 2 h run than before the 2 h run (P<0.05). The findings suggest that fatigue from prolonged endurance activity may introduce a resetting in the pituitary-adrenocortical component of the endocrine system, expressed either by intensified or by suppressed endocrine functions. Electronic Publication     

Changes in the degree of motor variability associated with experimental and chronic neck–shoulder pain during a standardised repetitive arm movement

The aim of the present study was to investigate the effect of experimental and chronic neck–shoulder pain on the magnitude of cycle-to-cycle variability of task timing, kinematics and muscle activation during repetitive arm movement performed for 3 or 5 min. In an experimental part, acute muscle pain was induced in healthy subjects by intramuscular injection of hypertonic saline in trapezius (n = 10) and infraspinatus (n = 10) muscles. In a clinical part, workers with (n = 12) and without (n = 6) chronic neck–shoulder pain were compared. Cycle-to-cycle standard deviations of task duration, arm and trunk movement in 3D and surface electromyographic (EMG) root mean square activity were computed to assess the degree of variability. The variability in task timing increased in presence of both experimental and chronic pain (P < 0.05) compared with non-painful conditions. Experimental pain increased the variability of the starting position of the arm (P < 0.05), the arm range of motion (P < 0.01), the arm and trunk movement area (P < 0.01) and the acceleration of the arm (P < 0.01). In the chronic pain condition, the variability of arm and trunk acceleration (P < 0.01) and EMG activity (P < 0.05) was decreased compared with healthy controls. These results indicate that pain alters the magnitude of motor variability, and that the transition from acute to chronic pain is accompanied by changes in motor patterns. Experimental pain likely resulted in a quest for a motor solution reducing nociceptive influx, while chronic pain was characterised by a diminished motor flexibility.     

Neuromuscular adaptation during prolonged strength training, detraining and re-strength-training in middle-aged and elderly people

Effects of a 24-week strength training performed twice weekly (24 ST) (combined with explosive exercises) followed by either a 3-week detraining (3 DT) and a 21-week re-strength-training (21 RST) (experiment A) or by a 24-week detraining (24 DT) (experiment B) on neural activation of the agonist and antagonist leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris, maximal isometric and one repetition maximum (1-RM) strength and jumping (J) and walking (W) performances were examined. A group of middle-aged (M, 37–44 years, n=12) and elderly (E, 62–77, n=10) and another group of M (35–45, n=7) and E (63–78, n=7) served as subjects. In experiment A, the 1-RM increased substantially during 24 ST in M (27%, P < 0.001) and E (29%, P < 0.001) and in experiment B in M (29%, P < 0.001) and E (23%, P < 0.01). During 21 RST the 1-RM was increased by 5% at week 48 (P < 0.01) in M and 3% at week 41 in E (n.s., but P < 0.05 at week 34). In experiment A the integrated electromyogram (IEMG) of the vastus muscles in the 1-RM increased during 24 ST in both M (P < 0.05) and E (P < 0.001) and during 21 RST in M for the right (P < 0.05) and in E for both legs (P < 0.05). The biceps femoris co-activation during the 1-RM leg extension decreased during the first 8-week training in M (from 29 ± 5% to 25 ± 3%, n.s.) and especially in E (from 41 ± 11% to 32 ± 9%, P < 0.05). The CSA increased by 7% in M (P < 0.05) and by 7% in E (P < 0.001), and by 7% (n.s.) in M and by 3% in E (n.s.) during 24 ST periods. Increases of 18% (P < 0.001) and 12% (P < 0.05) in M and 22% (P < 0.001) and 26% (P < 0.05) in E occurred in J. W speed increased (P < 0.05) in both age groups. The only decrease during 3 DT was in maximal isometric force in M by 6% (P < 0.05) and by 4% (n.s.) in E. During 24 DT the CSA decreased in both age groups (P < 0.01), the 1-RM decreased by 6% (P < 0.05) in M and by 4% (P < 0.05) in E and isometric force by 12% (P < 0.001) in M and by 9% (P < 0.05) in E, respectively, while J and W remained unaltered. The strength gains were accompanied by increased maximal voluntary neural activation of the agonists in both age groups with reduced antagonist co-activation in the elderly during the initial training phases. Neural adaptation seemed to play a greater role than muscle hypertrophy. Short-term detraining led to only minor changes, while prolonged detraining resulted in muscle atrophy and decreased voluntary strength, but explosive jumping and walking actions in both age groups appeared to remain elevated for quite a long time by compensatory types of physical activities when performed on a regular basis. Accepted: 2 May 2000     

Postactivation potentiation of knee extensor muscles in power- and endurance-trained, and untrained women

This study compared postactivation potentiation (PAP) in knee extensor muscles after a 10 s conditioning isometric maximal voluntary contraction (MVC) in female power- (PT, n = 12) and endurance-trained (ET, n = 12) athletes, and untrained (UT, n = 12) women aged 20–24 years. Isometric twitch characteristics of the knee extensor muscles were assessed in pre-MVC condition and during 15 min post-MVC period using supramaximal electrical stimulation of the femoral nerve by rectangular pulses of 1 ms duration. A significant (P < 0.05) potentiation of twitch peak torque (Pt, 30–51% in different groups), maximal rates of torque development (50–125%) and relaxation (76–124%) occurred immediately (2 s) post-MVC. PAP declined sharply at 1–3 min of recovery, whereas a significant potentiation of twitch Pt was still present for ET athletes at 1 min, and for UT women and PT athletes at 5 min of recovery, respectively. There were no significant (P > 0.05) changes in twitch contraction and half-relaxation times after a 10 s conditioning MVC. We concluded that PAP in knee extensor muscles is enhanced in PT but not in ET female athletes. The magnitude of PAP was greater when measured immediately after the conditioning MVC and its decline was slower in PT compared with ET athletes. Immediately post-MVC, twitch speed-related characteristics were potentiated to a greater extent than twitch Pt. The time-course of isometric twitch was not significantly altered by conditioning MVC.     

Effects of long-term training specificity on maximal strength and power of the upper and lower extremities in athletes from different sports

Maximal concentric one repetition maximum half-squat (1RM_HS), bench-press (1RM_BP), power-load curves during concentric actions with loads ranging from 30% to 100% of 1RM_HS and 1RM_BP were examined in 70 male subjects divided into five groups: weightlifters (WL, n=11), handball players (HP, n=19), amateur road cyclists (RC, n=18), middle-distance runners (MDR, n=10) and age-matched control subjects (C, n=12). The 1RM_HS values in WL, HP and RC were 50%, 29% and 28% greater, respectively, (P<0.001–0.01) than those recorded for MDR and C. The half-squat average power outputs at all loads examined (from 30% to 100%) in WL and HP (P<0.001 at 45% and 60% with HP) were higher (P<0.05–0.001) than those in MDR, RC and C. Average power output at the load of 30% of 1RM_HS in RC was higher (P<0.05) than that recorded in MDR and C. Maximal power output was produced at the load of 60% for HP, MDR and C, and at the load of 45% for WL and RC. The 1RM_BP in WL was larger (P<0.05) than those recorded in HP, RC, MDR and C. In the bench press, average muscle power outputs in WL and HP were higher (P<0.05–0.001) than those in MDR, RC and C, and were maximized at a load of 30% of 1RM for WL and HP, and at 45% for RC, MDR and C. In addition, the velocities that elicited the maximal power in the lower extremities were lower (≈0.75 m·s^–1) than those occurring in the upper extremities (≈1 m·s^–1). The data suggest that the magnitude of the sport-related differences in strength and/or muscle power output may be explained in part by differences in muscle cross-sectional area, fibre type distribution and in the muscle mechanics of the upper and lower limbs as well as by training background. Electronic Publication