Gymnastik- och idrottshögskolan, GIH

Walking Football (WF) is one type of recreational football increasing in popularity, targeting older adults. Further knowledge on the intensity and physical workload of WF, characteristics of the players, the social context, and reasons for playing WF is needed. Thus, the aim of the study was to characterize the individuals that regularly play WF and their experience of WF, and the physiological characteristics of the sport. Sixty-three players from three clubs taking part in organised WF in Sweden were included. The players participated in up to four WF-games and underwent performance tests and answered a questionnaire. The participants mean age was 70.9 years, ranging from 63 to 85 years with 71% (n = 27) of the men and 68% (n = 13) of the women having a BMI > 25. Fifty-one percent (n = 27) of the players had hypertension, and 73% (n = 39) regularly used prescription drugs due to illness. During WF, the players covered on average 2,409 m (2,509 m for men and 2,205 m for women, p = .001). Expressed in percentage of their age-estimated maximal heart rate, mean heart rate represented 80 ± 9 and 80 ± 8% of max for men, and 78 ± 9 and 79 ± 9% of max for women in the first and second halves, respectively, hence WF can be considered a moderate intensity activity for older adults. The main reason for WF participation was to socialize. WF includes a considerable number of accelerations and decelerations, making it more energetically and mechanically demanding than walking.

Background: Recently, it was shown that exogenously administered testosterone enhances endurance capacity in women. In this study, our understanding on the effects of exogenous testosterone on key determinants of oxygen transport and utilization in skeletal muscle is expanded.Methods: In a double-blinded, randomized, placebo-controlled trial, 48 healthy active women were randomized to 10 weeks of daily application of 10 mg of testosterone cream or placebo. Before and after the intervention, VO₂ max, body composition, total hemoglobin (Hb) mass and blood volumes were assessed. Biopsies from the vastus lateralis muscle were obtained before and after the intervention to assess mitochondrial protein abundance, capillary density, capillary-to-fiber (C/F) ratio, and skeletal muscle oxidative capacity.Results: Maximal oxygen consumption per muscle mass, Hb mass, blood, plasma and red blood cell volumes, capillary density, and the abundance of mitochondrial protein levels (i.e., citrate synthase, complexes I, II, III, IV-subunit 2, IV-subunit 4, and V) were unchanged by the intervention. However, the C/F ratio, specific mitochondrial respiratory flux activating complex I and linked complex I and II, uncoupled respiration and electron transport system capacity, but not leak respiration or fat respiration, were significantly increased following testosterone administration compared to placebo.Conclusion: This study provides novel insights into physiological actions of increased testosterone exposure on key determinants of oxygen diffusion and utilization in skeletal muscle of women. Our findings show that higher skeletal muscle oxidative capacity coupled to higher C/F ratio could be major contributing factors that improve endurance performance following moderately increased testosterone exposure.

Den militärmedicinska forskningsgruppen vid Åstrandlaboratoriet, Gymnastik- och Idrottshögskolan, Stockholm, har som forskningsuppgift med stöd från Försvarsmakten att studera och föreslå insatser för att upprätthålla stridsvärdet för trupp under långvarigt fysiskt arbete. Forskningen har hitintills resulterat i åtta rapporter, där fysisk arbetsförmåga studerats under olika förhållanden. Föreliggande rapport sammanfattar de huvudsakliga resultaten från dessa undersökningar men omfattar också en diskussion gällande skillnader och likheter mellan kvinnors jämfört med mäns adaptation till långvarigt och tungt arbete samt ett kort avsnitt om fortsatta undersökningar, byggda på tidigare resultat.

Purpose: To measure isokinetic peak torque during elbow, knee and trunk extension and flexion and muscle endurance during elbow and knee extension.

Method: Muscle endurance and peak torque were measured using Cybex methodology in totally 115 boys and 48 girls from 8 to 15 years of age most of them for five years.

Results: Knee muscle endurance was mainly unchanged while elbow fatigue index was lightly reduced from 11 to 15 years in both sexes with no difference between sexes. From the youngest ages to adolescence peak absolute (N.m) and normalized (N.m/kg body mass) torque increases in all measures with highest increase in the trunk and lowest in elbow activities. During elbow activity boys are stronger than girls from age 11. For trunk and knee activity the sex differences start at age 14 years. Knee, elbow and trunk extension/flexion ratios as well as knee/elbow both extension and flexion ratios are mainly unchanged with increasing age with no differences between sexes.

Conclusion: Data indicate that elbow isokinetic strength and endurance profile is partly different from corresponding data during knee and trunk activity.

Sjutton kvinnliga vältränade försökspersoner, åtta stycken med vana att bära tungt och nio stycken utan sådan vana, genomförde gång på löpband och mjukt underlag i hastigheterna 3 och 5 km/tim med bärvikter i ryggsäck på 20, 35 och 50 kg.Mjukt underlag i form av blå gymnastikmattor, indikerande gång i lätt terräng, ökade energiomsättningen under både hastigheterna mellan 10 och 15 %, jämfört med hårt underlag (löpband) med en grads lutning. Energiomsättningen ökade i genomsnitt lika mycket med ökad hastighet som med ökad bärvikt. Den individuella variationen vid en given bärvikt och hastighet är mycket stor. Beroende på bärvikt och hastighet kan energiomsättningen variera med 100 %. Dessa stora variationer i energiomsättning bör uppmärksammas vid beräkning av energitilldelning via kosten vid längre militära operationer.Energiomsättningen vid tyngsta belastningen – 50 kilo bärvikt och hastigheten 5 km/tim – belastade försökspersonerna på i genomsnitt 57 % av maximal syreupptagningsförmåga. I individuella fall var belastningen 72 % av maximal syreupptagningsförmåga. Dessa höga belastningar är oacceptabelt höga för transporter under längre tid och kan vara en orsak till belastningsskador.Förmågan att bära tungt sammanfaller med ökad kroppsvikt och benmuskelstyrka. Bärförmåga för mindre vikter, högst 35 kg, sammanfaller inte med någon av ovanstående faktorer. Således, för tyngre bärvikter vid förflyttningar bör selektion av soldater ske enligt de uppmätta parametrarna, medan vad gäller lättare vikter föreligger inte samma selektionskriterier.En slutsats från resultaten av denna undersökning är den ursprungliga uttagningen till tunga arbetsuppgifter inom försvaret bör genomföras med tunga arbetsbelastningar, motsvarande de i denna undersökning. I kommande rapport sammanfattas studierna på män och kvinnors bärförmåga, likheter och olikheter mellan könen, möjliga selektionskriterier samt rekommendationer med utgångspunkt från genomförda undersökningar och resultat från olika andra undersökningar.

INTRODUCTION: The ability to carry heavy loads is an important and necessary task during numerous outdoor activities and especially in military operations. The aim of this study was to investigate factors associated with load-carrying ability in men and women with and without extensive load-carrying experience.

MATERIALS AND METHODS: The energy expenditure during carrying no load, 20, 35, and 50 kg at 2 walking speeds, 3 and 5 km h-1, was studied in 36 healthy participants, 19 men (30 ± 6 years, 82.5 ± 7.0 kg) and 17 women (29 ± 6 years, 66.1 ± 8.9 kg), experienced (>5 years) in carrying heavy loads (n = 16, 8 women) or with minor or no such experience (n = 20, 9 women). A standard backpack filled with weights to according carry load was used during the walks. Anthropometric data, leg muscle strength, as well as trunk muscle endurance and muscle fiber distribution of the thigh, were also obtained. Extra Load Index (ELI)-the oxygen uptake (VO2) during total load over unloaded walking-was used as a proxy for load-carrying ability at 20, 35, and 50 kg (ELI20, ELI35, and ELI50, respectively). In addition to analyzing factors of importance for the ELI values, we also conducted mediator analyses using sex and long-term carrying experience as causal variables for ELI as the outcome value. The study was approved by the Regional Ethics Committee in Stockholm, Sweden.

RESULTS: For the lowest load (20 kg), ELI20, was correlated with body mass but no other factors. Walking with 35 and 50 kg load at 5 km h-1 body mass, body height, leg muscle strength, and absolute VO2max were correlated, while relative VO2max, trunk muscle endurance, and leg muscle fiber distribution were not correlated to ELI35 and ELI50.ELI50 at 5 km h-1 differed between the sexes. This difference was only mediated by the difference in body mass. Neither muscle fiber distribution, leg muscle strength, trunk muscle endurance, and body height nor did absolute or relative VO2max explain the difference.Participants with long-term experience of heavy load carrying had significant lower ELI20 and ELI50 values than those with minor or no experience, but none of the above studied factors could explain this difference.

CONCLUSION: The study showed that body mass, without sex differences, and experience of carrying heavy loads are the dominant factors for the ability to carry heavy loads. Even though the effect of experience alludes to the need for extensive carrying training, no causality can be proven. Load carry training intervention studies is suggested for future investigations.

BACKGROUND: Reliable physical activity measurements in community-dwelling older adults are important to determine effects of targeted health promotion interventions. Many exercise interventions aim to improve time spent sedentary (SED), in light-intensity-physical-activity (LPA) and moderate-to-vigorous-intensity-physical-activity (MVPA), since these parameters have independently proposed associations with health and longevity. However, many previous studies rely on self-reports which have lower validity compared to accelerometer measured physical activity patterns. In addition, separating intervention-effects from reactivity measurements requires sufficient test-retest reliability for accelerometer assessments, which is lacking in older adults.

OBJECTIVES: The study objective was to investigate the reliability of sensor-based PA-patterns in community-dwelling older adults. Furthermore, to investigate change over time of physical activity patterns and examine any compensatory-effect from the eight-week supervised exercise-intervention.

METHODS: An exercise-group (n = 78, age-range:65-91yrs) performed two 1h-exercise sessions/week during eight-weeks. PA-pattern was assessed (using hip-worn accelerometers), twice before and once during the last-week of the intervention. A control-group (n = 43, age-range:65-88yrs) performed one pre-test and the end-test with no exercise-intervention. A dependent-t-test, mean-difference (95%-CI), limits-of-agreement and intraclass-correlation-coefficient-ICC were used between the two pre-tests. Repeated-measures-ANOVA were used to analyze any intervention-effects.

RESULTS: The exercise-groups´ two pre-tests showed generally no systematic change in any PA- or SED-parameter (ICC ranged 0.75-0.90). Compared to the control group, the exercise intervention significantly (time x group-interaction, p<0.05) increased total-PA-cpm (exercise-group/control-group +17%/+7%) and MVPA-min/week (+41/-2min) and decreased %-of-wear-time for SED-total (-4.7%/-2.7%) and SED-bouts (-5.7%/-1.8%), and SED-bouts min/d (-46/-16min). At baseline level, no significant differences were found between the two groups for any parameter.

CONCLUSIONS: The current study presents a good test-retest-reliability of sensor-based-one-week-assessed-PA-pattern in older-adults. Participating in an 8-week supervised exercise intervention improved some physical activity and sedentary parameters compared to the control group. No compensatory-effect was noted in the intervention-group i.e., no decrease in any PA-parameter or increase in SED at End-test (in %-of-wear-time, min/day or total-PA).

INTRODUCTION: Physical fitness is strongly associated with daily physical function, health, and longevity in older adults. Field-based tests may provide a reasonable alternative compared to advanced laboratory testing. Separating postexercise test scores from reactivity measurements requires sufficient test-retest reliability. Postexercise test scores with reliability analyses of field-based fitness tests in older adults are lacking. The present study aimed to examine the test-retest reliability of some novel easily accommodated fitness test measurements and compare pretest scores with postexercise results in these tests along with other field-based fitness tests in older adults.

METHODS: Totally 1,407 community-dwelling older adults (69% female), x̄ = 71.5 ± 5.0 (65-84 years), performed twelve field-based fitness tests at pretest 1, pretest 2 and a posttest after an 8-week exercise period (twice weekly 1 h of combined strength and aerobic training). T tests, intra-class correlation, limits of agreement, standard error of measurement, and coefficient of variance were performed between pre-1 and pre-2 tests, and repeated measures ANOVA and partial eta squared effect size for postexercise differences for men and women in 5-year age groups ranging from 65 to 84 years.

RESULTS: Between pre-1 and pre-2 tests a significant difference was noted in some of the novel fitness test measurements but generally not, e.g., in isometric trunk flexion and step-up height on either leg among all sex and age groups. In most of these novel fitness test measurements, no significant differences occurred between the two pretests. Examples of results from the pre-2 test to the posttest were isometric trunk flexion 45° endurance and isometric trunk extension endurance improved significantly for both sexes in age groups 65-74 years. Women, but not men, improved the maximal step-up height for both legs in most age groups. The speed in the 50 sit-to-stand improved significantly for most age groups in both sexes. Six-min walk distance improved significantly for most age groups in women but among men only in 65-69 years. In the timed-up-and-go test, significant improvements were seen for all age groups in women and in men 70-79 years. No postexercise improvements were generally observed for grip strength or balance.

CONCLUSIONS: In most of the novel fitness test measures, no significant difference was noted between the two pretests in the assessed sex and age groups. Results after the 8-week exercise period varied between sex and age groups, with significant improvements in several of the twelve studied fitness tests. These findings may be valuable for future projects utilizing easily accommodated physical fitness tests in older adults.

PURPOSE: To study the effect of inhaling a beta-agonist (salbutamol) compared to placebo on skiing and cycling performance in well-trained elite athletes.

METHODS: Three different exercise protocols were used, all with a cross-over double blind placebo-controlled design. Participants inhaled 800 µg salbutamol or a placebo prior to the test, which was repeated on a following day with the participants inhaling the other substance. Fifteen junior elite skiers performed four free-style high intensity sprints (1100 m/work time 3.5-4.5 min). Twelve elite cyclists carried out a short cycling protocol, starting with two 5 min submaximal workloads followed by a maximal intermittent performance test to exhaustion. Another 12 elite cyclists performed the maximal intermittent performance test to exhaustion after a 150 min long submaximal cycling protocol.

RESULTS: Group mean time for the ski sprints increased, with no difference between treatment groups. In the short cycling protocol time to exhaustion was 9.1% (95% CI 52-161) lower after inhaling salbutamol compared to placebo and in the long cycling protocol time to exhaustion was 9.1% (95% CI - 121-267) lower after inhaling salbutamol compared to placebo. Blood lactate, heart rate and ventilation increased during submaximal exercise with salbutamol compared to placebo in the short cycling protocol (p < .05).

CONCLUSION: This study could not confirm any positive performance effects from inhaling 800 µg salbutamol compared to placebo in skiing and high-intensity intermittent cycling performance. Instead, time to exhaustion in the maximal intermittent performance test was lower in both cycling protocols. HighlightsThere was no difference in performance time between salbutamol and placebo treatment in real-life applicable repeated ski sprints.Time to exhaustion in the maximal intermittent performance test was 9.1% lower after inhaling salbutamol compared to placebo, both when performed after 10 and 150 min of submaximal cycling.

Nitton manliga vältränade försökspersoner, 9 st med vana att bära tungt och 10 st utan sådan vana, genomförde gång på mjukt underlag i hastigheterna 3 och 5 km/tim med bärvikter i ryggsäck på 20, 35 och 50 kg.

Energiomsättningen ökade i genomsnitt lika mycket med ökad hastighet som med ökad bärvikt. Mjukt underlag, indikerande gång i lätt terräng, ökade energiomsättningen under både hastigheterna med c:a 20 %, jämfört med hårtunderlag (löpband). Den individuella variationen vid en given bärvikt och hastighet är mycket stor. Beroende på bärvikt och hastighet kan energiomsättningen variera med 100%.  Dessa stora variationer i energiomsättning bör uppmärksammas vid beräkning av energitilldelning via kosten vid längre militära operationer.

Energiomsättningen vid tyngsta belastningen – 50 kilo bärvikt och hastigheten 5 km/tim – belastade försökspersonerna på i genomsnitt 44 % av maximal syreupptagningsförmåga. I individuella fall var belastningen 60%. Dessa höga belastningar är oacceptabelt höga för transporter under längre tid och kan vara en orsak till belastningsskador.

Förmågan att bära tungt sammanfaller med ökad kroppsstorlek – både längd och vikt – ålder, maximal syreupptagningsförmåga mätt i L/min men inte i ml/min och kg kroppsvikt, benmuskelstyrka men inte bålmuskelstyrka samt andelen muskelfibrer i lårmuskeln av typ 1. Flera men inte alla av dessa förmågor kan säkert till viss del tränas upp. Bärförmåga för mindre vikter, högst 35 kg, sammanfaller inte med några av ovanstående faktorer, bortsett från ålder. Således, för tyngre bärvikter vid förflyttningar bör selektion av soldater ske enligt de uppmätta parametrarna, medan vad gäller lättare vikter föreligger inte samma selektionkriterier.

En slutsats från resultaten av denna undersökning är den ursprungliga uttagningen till tunga arbetsuppgifter inom försvaret bör genomföras med tunga arbetsbelastningar, motsvarande de i denna undersökning. Avsikten i fortsättningen av denna undersökningsserie är att fastställa ny testmetodik och procedur för denna selektion samt genomföra tester på kvinnor.

Objective To investigate the effects of a moderate increase in serum testosterone on physical performance in young, physically active, healthy women.Methods A double blind, randomised, placebo controlled trial was conducted between May 2017 and June 2018 (ClinicalTrials.gov ID: NCT03210558). 48 healthy, physically active women aged 18–35 years were randomised to 10 weeks of treatment with 10 mg of testosterone cream daily or placebo (1:1). All participants completed the study. The primary outcome measure was aerobic performance measured by running time to exhaustion (TTE). Secondary outcomes were anaerobic performance (Wingate test) and muscle strength (squat jump (SJ), counter movement jump (CMJ) and knee extension peak torque). Hormone levels were analysed and body composition assessed by dual energy X-ray absorptiometry.Results Serum levels of testosterone increased from 0.9 (0.4) nmol/L to 4.3 (2.8) nmol/L in the testosterone supplemented group. TTE increased significantly by 21.17 s (8.5%) in the testosterone group compared with the placebo group (mean difference 15.5 s; P=0.045). Wingate average power, which increased by 15.2 W in the testosterone group compared with 3.2 W in the placebo group, was not significantly different between the groups (P=0.084). There were no significant changes in CMJ, SJ and knee extension. Mean change from baseline in total lean mass was 923 g for the testosterone group and 135 g for the placebo group (P=0.040). Mean change in lean mass in the lower limbs was 398 g and 91 g, respectively (P=0.041).Conclusion The study supports a causal effect of testosterone in the increase in aerobic running time as well as lean mass in young, physically active women.

It is well established that testosterone administration induces muscle fiber hypertrophy and myonuclear addition in men, however, it remains to be determined whether similar morphological adaptations can be achieved in women. The aim of the present study was therefore to investigate whether exogenously administered testosterone alters muscle fiber morphology in skeletal muscle of young healthy, physically active women. Thirty-five young (20-35 years), recreationally trained women were randomly assigned to either 10-week testosterone administration (10 mg daily) or placebo. Before and after the intervention, hormone concentrations and body composition were assessed, and muscle biopsies were obtained from the vastus lateralis. Fiber type composition, fiber size, satellite cell- and myonuclei content, as well as muscle capillarization were assessed in a fiber type-specific manner using immunohistochemistry. Following the intervention, testosterone administration elevated serum testosterone concentration (5.1-fold increase, P=0.001), and induced significant accretion of total lean mass (+1.9%, P=0.002) and leg lean mass (+2.4%, P=0.001). On the muscle fiber level, testosterone increased mixed fiber cross-sectional area (+8.2%, P=0.001), an effect primarily driven by increases in type II fiber size (9.2%, P=0.006). Whereas myonuclei content remained unchanged, a numerical increase (+30.8%) was found for satellite cells associated with type II fibers in the Testosterone group. In parallel with fiber hypertrophy, testosterone significantly increased capillary contacts (+7.5%, P=0.015) and capillary-to-fiber ratio (+9.2%, P=0.001) in type II muscle fibers. The current study provides novel insight into fiber type-specific adaptations present already after 10 weeks of only moderately elevated testosterone levels in women.