User Experience during an Immersive Virtual Reality-Based Cognitive Task: A Comparison between Estonian and Italian Older Adults with MCI.

Mild cognitive impairment (MCI) is an early stage of cognitive abilities loss and puts older adults at higher risk of developing dementia. Virtual reality (VR) could represent a tool for the early assessment of this pathological condition and for administering cognitive training. This work presents a study evaluating the acceptance and the user experience of an immersive VR application representing a supermarket. As the same application had already been assessed in Italy, we aimed to perform the same study in Estonia in order to compare the outcomes in the two populations. Fifteen older adults with MCI were enrolled in one Rehabilitation Center of Estonia and tried the supermarket once. Afterwards, they were administered questionnaires aimed at evaluating their technology acceptance, sense of presence, and cybersickness. Estonian participants reported low side effects and discrete enjoyment, and a sense of presence. Nonetheless, their intention to use the technology decreased after the experience. The comparison between Italian and Estonian older adults showed that cybersickness was comparable, but technology acceptance and sense of presence were significantly lower in the Estonian group. Thus, we argue that: (i) cultural and social backgrounds influence technology acceptance; (ii) technology acceptance was rather mediated by the absence of positive feelings rather than cybersickness.

Single session exercises and concurrent functional electrical stimulation are more effective on muscles' force generation than only exercises in spinal cord injured persons: a feasibility study.

OBJECTIVES: To evaluate impact of first therapy session, containing functional electrical stimulation (FES) and therapeutic exercises (TE) on erector spinae (ES) and rectus abdominis (RA) force generation in persons with spinal cord injury (SCI). METHODS: Five men with SCI were divided in two groups - FES+TE received concurrent FES on ES and RA and TE, TE only TE. Participants performed exercises for improving sitting balance and posture. Muscles' electrical activity was evaluated by electromyography; amplitude (AEMG) and median frequency (MF) were used for analysis. RESULTS: AEMG of ES left (L) increased 292.9% (g=-0.92), right (R) 175% (g=-1.01), RA L 314.3% (g=-0,81, P<0.05), R 266.7% (g=-0.08) in FES+TE. AEMG of ES L increased 47.6% (g=-0.46), R 96.4% (g=-0.95); RA L 7.1% (g=-0.97), but R decreased 6.7% (g=0.12) in TE. MF of ES L increased 108.5% (g=-0.74), R 184% (g=-1.25); RA L 886.7% (g=3-05, P<0.05), R 817.6% (g=-2.55, P<0.05) in FES+TE. MF of ES L increased 95.2% (g=-1.02), R 161.4% (g=-1.64); RA L 3,2% (g=-0.06), R 30.8% (g=-0.46) in TE. CONCLUSIONS: In SCI persons, single session exercises and concurrent functional electrical stimulation may be more effective on muscles` force generation than only exercises. However, replication of the results is needed before clinical implementation.

The Effect of Functional Electrical Stimulation and Therapeutic Exercises on Trunk Muscle Tone and Dynamic Sitting Balance in Persons with Chronic Spinal Cord Injury: A Crossover Trial.

Background and objectives: Functional electrical stimulation (FES) has shown good results in improving static and dynamic sitting balance in persons with spinal cord injuries. There is limited information about how regular surface FES combined with therapeutic exercise (TE) affect dynamic sitting balance and muscle tone. The objective of this study was to evaluate the effectiveness of a six-week physical therapy program consisting of FES and TE on muscle tone and sitting balance in persons with spinal cord injury (SCI). It was also important to explore the relationship between muscle tone and dynamic sitting balance. The third objective was to assess the change of characteristics over a six month period, when no intervention was carried out. Material and methods: Five men with SCI were alternately allocated to two study groups: SCI_FES+TE and SCI_TE. Eight healthy control group participants were recruited to collect reference data. SCI participants' intervention lasted for six weeks in their homes. SCI_FES+TE conducted exercises with FES applied on erector spinae (ES) and rectus abdominis (RA) muscles. SCI_TE conducted exercises only. Muscle oscillation frequency (MOF; characterizing muscle tone) and limits of stability (LOS; characterizing sitting balance) were measured. A crossover study design was used. The time between the initial intervention and the crossover was seven months (ClinicalTrials registration ID NCT03517787). Results: MOF in SCI_FES+TE increased by 6.0% for ES and 6.1% for RA muscles. LOS of flexion increased 30.1% in SCI_FES+TE. Increase in lateral directions was similar for both study groups. Moderate to high negative correlation was found between MOF and LOS. After seven months, MOF of ES decreased 0.8%, MOF or RA decreased 1.4%, LOS of flexion decreased 31.9%, and LOS of lateral flexion to the left decreased 46.4%. Conclusions: The six-week therapy program combining FES and TE increased trunk muscle tone and dynamic sitting balance in flexion more than TE alone. Higher antagonist muscle tone negatively affects dynamic sitting balance and center of pressure (COP) trajectory distance in various directions. After seven months, a slight decline in trunk muscles tone values and an extensive decrease in sitting balance values were noticed.

Body Composition, Neuromuscular Performance, and Mobility: Comparison Between Regularly Exercising and Inactive Older Women.

The purpose of this study was to evaluate the differences in body composition, neuromuscular performance, and mobility in healthy, regularly exercising and inactive older women, and examine the relationship between skeletal muscle indices and mobility. Overall, 32 healthy older women participated. They were divided into groups according to their physical activity history as regularly exercising (n = 22) and inactive (n = 10) women. Body composition, hand grip strength, leg extensor muscle strength, rapid force development, power output, and mobility indices were assessed. Regularly exercising women had lower fat mass and higher values for leg extensor muscle strength and muscle quality, and also for mobility. Leg extensor muscle strength and power output during vertical jumping and appendicular lean mass per unit of body mass were associated with mobility in healthy older women. It was concluded that long-term regular exercising may have beneficial effects on body composition and physical function in older women.

Upper Extremity and Cue Kinematics, and Shoulder Muscle Electromyographic Activity of Novus Players of Different Skill Levels.

Our aim with the current study was to compare upper extremity and cue kinematics, and electromyographic (EMG) activation of shoulder muscles during novus (a special form of billiards) shots of different difficulty levels. Ten proficient and 10 less-skilled novus players performed 3 types of novus shots (penalties, cuts, rebounds) 10 times each. During each shot, elbow flexion and cue-forearm angles (using a movement analysis system), and surface EMG activity of the trapezius, posterior, and lateral deltoid muscles of each subject's dominant side, were measured. Data were compared between more- and less-skilled players, and successful compared with unsuccessful shots. Elbow flexion angle among the more-skilled players was 24.5% larger (P < .001) during unsuccessful cut shots than successful ones. The more-skilled players performed successful penalty and rebound shots with 26.8% and 49.8% lower (P < .01 and P < .001, respectively) EMG activity of the trapezius muscle than unsuccessful ones. Less-skilled players' shots were characterized by higher EMG activity in the trapezius muscle. The obtained findings suggest that the more-skilled novus players had acquired a different muscle recruitment pattern than less-skilled players.

Association between osteocalcin and cognitive performance in healthy older adults.

INTRODUCTION: cognitive deterioration and reductions of bone health coincide with increasing age. We examine the relationship between bone composition and plasma markers of bone remodelling with measures of cognitive performance in healthy adults. METHODS: this cross-sectional study included 225 old (52% women, mean age: 74.4 ± 3.3 years) and 134 young (52% women, mean age: 23.4 ± 2.7 years) adult participants from the MyoAge project. Whole body bone mineral density was measured by dual-energy X-ray absorptiometry. Blood analyses included a panel of bone-related peptides (dickkopf-1, osteoprotegerin, osteocalcin (OC), osteopontin, sclerostin, parathyroid hormone and fibroblast growth factor 23), as well as serum calcium and 25-hydroxy vitamin D assays. A selection of cognitive domains (working memory capacity, episodic memory, executive functioning and global cognition) was assessed with a standardised neuropsychological test battery. RESULTS: adjusting for covariates and multiple testing revealed that plasma OC levels were positively associated with measures of executive functioning (ß = 0.444, P < 0.001) and global cognition (ß = 0.381, P = 0.001) in the older women. DISCUSSION: these correlative results demonstrate a positive association between OC, a factor known to regulate bone remodelling, with cognitive performance in older non-demented women. Further work should address possible mechanistic interpretations in humans.

The Impact of Different Diagnostic Criteria on the Prevalence of Sarcopenia in Healthy Elderly Participants and Geriatric Outpatients.

BACKGROUND: A consensus on the diagnostic criteria for sarcopenia, a common syndrome in the elderly, has not been reached yet. Prevalence rates vary between studies due to the use of different criteria encompassing different measures, correction factors and cutoff points. OBJECTIVE: This study compared prevalence rates of sarcopenia using nine sets of diagnostic criteria applied in two different elderly populations. METHODS: The study population encompassed 308 healthy elderly participants (152 males, 156 females; mean age 74 years) and 123 geriatric outpatients (54 males, 69 females; mean age 81 years). Diagnostic criteria included relative muscle mass, absolute muscle mass, muscle strength and physical performance. RESULTS: Prevalence rates of sarcopenia varied between 0 and 15% in healthy elderly participants and between 2 and 34% in geriatric outpatients. CONCLUSION: This study clearly demonstrates the dependency of sarcopenia prevalence rates on the applied diagnostic criteria.

Postural stability in relation to anthropometric and functional characteristics in women with knee osteoarthritis following total knee arthroplasty.

INTRODUCTION: Due to the controversial information about postural stability in patients with lower limb joints osteoarthritis (OA), the following main questions are raised: how serious is the postural stability disturbance and which factors have an impact on postural stability before and after total knee arthroplasty (TKA). MATERIALS AND METHODS: Force plate was used to assess postural stability and custom-made dynamometer was used to assess isometric maximal voluntary contraction (MVC) force of leg extensor muscles; besides, knee pain and knee range of motion (ROM) was evaluated in 14 female patients (aged 46-68 years) with knee OA 1 day before, and 3 and 6 months following TKA and once in healthy controls (aged 48-70). Relationship between postural stability during standing and selected anthropometric and functional characteristics were investigated with Spearman's correlation coefficients. RESULTS: Remarkable reduction of knee pain and improvement in active ROM for the operated leg were shown after unilateral TKA. MVC force of leg extensor muscles achieved the preoperative level half a year after TKA. The centre of pressure (COP) of sway displacement in anterioposterior (AP) and mediolateral direction and the equivalent area of COP sway for the operated leg did not differ before, 3 and 6 months after TKA and compared to the non-operated leg. The trace speed was 6 months after TKA equal to the preoperative level. Only the COP of sway displacement in AP direction is significantly greater in knee OA patients both before and after TKA compared with healthy controls. CONCLUSIONS: Knee OA patients' postural stability characteristics did not differ significantly both before and after TKA. Compared to healthy controls, the COP of sway displacement in AP direction is mostly disturbed. Correlation analysis confirms that increased postural sway is associated with an increased equivalent area of COP. In knee OA patients higher body mass index ensures reduced trace speed and lower knee ROM. LEVEL OF EVIDENCE: Prospective comparative study, Level II.

High dose vitamin D supplementation decreases the risk of deficiency in male conscripts, but has no effect on physical performance-A randomized study.

Purpose: Physical load during military training might increase the need for vitamin D; therefore, supplementation could be beneficial for 25(OH)D serum levels and physical performance. Methods: One hundred and twelve male conscripts were randomized into two vitamin D oil capsule supplementation groups: 55 participants in the 600 IU group and 57 in the 4000 IU group with a follow-up period from July 2021 to May 2022. Physical fitness tests were performed in July, October and May. Hand grip strength tests were performed in July, October and January. Blood serum (25(OH)D), parathyroid hormone PTH), calcium and ionized calcium (i-Ca) values were measured in July, October, January and May. Results: The 600 IU group had a lower (p < 0.001) value of 25(OH)D at all time points compared to the 4000 IU group, except at baseline. None of the subjects in the 600 IU group reached sufficient levels of 75 nmol/L of 25(OH)D in January and May. In May, 60% of participants in the 600 IU group and 30% in the 4000 IU group had 25(OH)D levels under 50 nmol/L. No significant differences in PTH or i-Ca values were found between the study groups at any time point. No significant differences at any time point were found in the physical fitness test or hand grip strength test between the groups. Conclusion: A 10-month vitamin D supplementation with 4000 IU decreased the incidence of vitamin D deficiency (<75 nmol/L) in young, male army conscripts during wintertime, but no differences in physical performance were found compared to 600 IU supplementation. Level of Evidence: Level I, Prospective randomized study.

Seasonal Variation in Vitamin D Status Does Not Interfere with Improvements in Aerobic and Muscular Endurance in Conscripts during Basic Military Training.

Considering a lack of respective data, the primary objective of this study was to assess whether seasonal variation in vitamin D status (D-status) affects the extent of improvement in physical performance (PP) in conscripts during basic military training (BMT). D-status, PP and several blood parameters were measured repeatedly in conscripts whose 10-week BMT started in July (cohort S-C; n = 96) or in October (cohort A-C; n = 107). D-status during BMT was higher in S-C compared to A-C (overall serum 25(OH)D 61.4 ± 16.1 and 48.5 ± 20.7 nmol/L, respectively; p < 0.0001). Significant (p < 0.05) improvements in both aerobic and muscular endurance occurred in both cohorts during BMT. Pooled data of the two cohorts revealed a highly reliable (p = 0.000) but weak (R2 = 0.038-0.162) positive association between D-status and PP measures both at the beginning and end of BMT. However, further analysis showed that such a relationship occurred only in conscripts with insufficient or deficient D-status, but not in their vitamin D-sufficient companions. Significant (p < 0.05) increases in serum testosterone-to-cortisol ratio and decreases in ferritin levels occurred during BMT. In conclusion, a positive association exists between D-status and PP measures, but seasonal variation in D-status does not influence the extent of improvement in PP in conscripts during BMT.

Physiological and functional evaluation of healthy young and older men and women: design of the European MyoAge study.

Within the European multi-centre MyoAge project, one workpackage was designed to investigate the contribution of age-related changes to muscle mass, contractile characteristics and neural control in relation to reductions in mobility in older age. The methodology has been described here. Test centres were located in Manchester, UK; Paris, France; Leiden, The Netherlands; Tartu, Estonia and Jyväskylä, Finland. In total, 182 young (18-30 years old, 52.2 % female) and 322 older adults (69-81 years old, 50 % female) have been examined. The participants were independent living, socially active and free from disease that impaired mobility levels. The older participants were selected based on physical activity levels, such that half exceeded current recommended physical activity levels and the other half had lower physical activity levels than is recommended to maintain health. Measurements consisted of blood pressure; anthropometry and body composition (dual-energy X-ray absorptiometry and magnetic resonance imaging); lung function; standing balance and cognitive function (CANTAB). Mobility was assessed using the Timed Up and Go, a 6 min walk, activity questionnaires and accelerometers to monitor habitual daily activities. Muscle strength, power, fatigue and neural activation were assessed using a combination of voluntary and electrically stimulated contractions. Fasting blood samples and skeletal muscle biopsies were collected for detailed examination of cell and molecular differences between young and older individuals. The results from this study will provide a detailed insight into "normal, healthy" ageing, linking whole-body function to the structure and function of the neuromuscular system and the molecular characteristics of skeletal muscle.

Circulating levels of adipokines and IGF-1 are associated with skeletal muscle strength of young and old healthy subjects.

It is known that adipose tissue mass increases with age, and that a number of hormones, collectively called adipokines, are produced by adipose tissue. For most of them it is not known whether their plasmatic levels change with age. Moreover, it is known that adipose tissue infiltration in skeletal muscle is related to sarcopenia and loss of muscle strength. In this study we investigated the age-related changes of representative adipokines and insulin-like growth factor (IGF)-1 and their effect on muscle strength. We studied the association between circulating levels of adiponectin, leptin, resistin and IGF-1 and muscle strength. This cross-sectional study included 412 subjects of different age (152 subjects aged 18-30 years and 260 subjects aged 69-81 years) recruited within the framework of the European research network project "Myoage". The levels of adiponectin (both in male and female subjects) and leptin (only in males) were significantly higher in old subjects compared to young, while those of IGF-1 were lower in old subjects. In old subjects adiponectin, resistin and the resistin/IGF-1 ratio (but not IGF-1 alone) were inversely associated with quadriceps torque, while only adiponectin was inversely associated with handgrip strength independently from percentage of fat mass, height, age, gender and geographical origin. The ratio of leptin to adiponectin was directly associated with handgrip strength in both young and old subjects. These results suggest that in humans the age-associated loss of strength is associated with the levels of representative adipokines and IGF-1.

Leg extensor muscle strength, postural stability, and fear of falling after a 2-month home exercise program in women with severe knee joint osteoarthritis.

BACKGROUND AND OBJECTIVE. The aim of this study was to compare the leg extensor muscle strength, the postural stability, and the fear of falling in the women with severe knee joint osteoarthritis (OA) before and after a 2-month home exercise program (HEP). MATERIAL AND METHODS. In total, 17 women aged 46-72 years with late-stage knee joint OA scheduled for total knee arthroplasty participated in this study before and after the 2-month HEP with strengthening, stretching, balance, and step exercises. The isometric peak torque (PT) of the leg extensors and postural stability characteristics when standing on a firm or a foam surface for 30 seconds were recorded. The fear of falling and the pain intensity (VAS) were estimated. RESULTS. A significant increase in the PT and the PT-to-body weight (PT-to-BW) ratio of the involved leg as well as the bilateral PT and the PT-to-BW ratio was found after the 2-month HEP compared with the data before the HEP (P<0.05). The PT and the PT-to-BW ratio of the involved leg were significantly lower compared with the uninvolved leg before the HEP (P<0.05). The center of the pressure sway length (foam surface) decreased significantly after the HEP (P<0.05). Significant correlations were found between the PT of the involved leg and the bilateral PT and the fear of falling and between the PT of the involved leg and the postural sway (foam surface) before the HEP. CONCLUSIONS. After the 2-month HEP, the leg extensor muscle strength increased and the postural sway length on a foam surface decreased. The results indicate that the increased leg extensor muscle strength improves postural stability and diminishes the fear of falling in women with late-stage knee joint OA.

Severe deficiency of vitamin D has no negative effect on physical performance during military training.

BACKGROUND: Decreased physical fitness and inferior physical performance are potentially life-threatening risk factors in a combat situation. To examine the effect of vitamin D on physical performance, a prospective study of young men conscripts in the Estonian Army was designed. The hypothesis of the study was that severe deficiency of vitamin D has a negative effect on physical performance. METHODS: All conscripts (N.=410) entering 10-month military service in July 2015 at the Kuperjanov Battalion were asked to participate. Initially, a total of 98 conscripts volunteered to participate. A prospective longitudinal study with a 10-month follow-up period was performed. The Army Physical Fitness Test (APFT) was performed three times, and hand grip strength, and blood serum values of 25(OH)D, parathyroid hormone (PTH) and calcium (Ca) were measured four times. RESULTS: A significant decrease in the levels of 25(OH)D compared with baseline values were found, with a lowest mean value of 31.9 nmol/L in March 2016 (P<0.001). No significant differences were found in serum Ca levels. In March 2016, PTH was significantly higher in the severe deficiency group (<25 nmol/L of 25(OH)D) (P=0.02). No significant differences were found in terms of the APFT or hand grip strength between conscripts with severe deficiency of 25(OH)D or values >25 nmol/L. The main finding of the present study was that severe 25(OH)D deficiency was common among male conscripts during the winter season but had no negative effect on physical performance in terms of the APFT test and hand grip strength test. CONCLUSIONS: Severe vitamin D deficiency during the winter season is common but has no negative effect on physical performance in young, physically active men in military service.

Quadriceps femoris muscle function prior and after total knee arthroplasty in women with knee osteoarthritis.

PURPOSE: The aim of the present study was to evaluate an isometric voluntary force generation and relaxation capacity of the quadriceps femoris (QF) muscle prior and after total knee arthroplasty (TKA). METHODS: Isometric maximal voluntary contraction force, rate of force development, voluntary activation, half-relaxation time, and latency of contraction of the QF muscle were recorded in 12 female patients (aged 49-68 years) with knee osteoarthritis one day before, 3 and 6 months following TKA in the operated and nonoperated leg. Knee pain intensity was assessed by visual analog scale, and Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire was used to assess knee problems during daily living. RESULTS: A significant decrease in knee pain and significant increase in KOOS were established after TKA. Maximal voluntary isometric force in the operated leg was lower (P < 0.05) before, 3 and 6 months after TKA as compared to the nonoperated leg. Rate of force development of the QF muscle in the operated leg compared to the nonoperated leg was significantly lower (P < 0.05) 3 and 6 months after TKA. Voluntary activation, latency of contraction, and half-relaxation time of the QF muscle did not differ significantly before, 3 and 6 months after TKA. CONCLUSIONS: The present study indicated reduced maximal and explosive strength of quadriceps femoris muscle in the operated leg 3 and 6 months after TKA with no significant changes in voluntary activation, and capacity for rapid contraction and relaxation. LEVEL OF EVIDENCE: Prospective comparative study, Level II.

Shoulder muscle isometric strength and active range of motion in patients with frozen shoulder syndrome after manipulation under anesthesia.

BACKGROUND AND OBJECTIVE: Frozen shoulder syndrome (FSS) causes pain and restriction of movement in the shoulder. The aim was to assess changes in shoulder muscle isometric maximal voluntary contraction (MVC) force and active range of motion (AROM) in patients with frozen shoulder syndrome (FSS) after manipulation under general anesthesia (MUA). MATERIAL AND METHODS: In total, 18 patients with FSS (9 women and 9 men) with a mean age of 53.6 years (SD, 9.7) participated in this study. MVC force of shoulder flexors, adductors, and internal and external rotators was measured by a handheld dynamometer. AROM in the same directions was measured goniometrically. The patients were screened according to the intensity of pain by day and at night. The data were collected before MUA and 1 and 6 months after MUA. A significant reduction in MVC force and AROM was noted before MUA in the involved extremity as compared with the uninvolved extremity (P<0.05). These parameters for the involved extremity were significantly increased 1 month after MUA (P<0.05). However, 6 months after MUA, MVC force and AROM did not differ significantly compared with the uninvolved extremity (P>0.05), whereas AROM of flexion and external rotation remained significantly reduced (P<0.05). A significant reduction in shoulder pain by day and at night was recorded 1 and 6 months after MUA (P<0.05). CONCLUSIONS: In the patients with FSS, the fastest improvement of MVC force and AROM occurred following the first month after MUA. However, 6 months after MUA, shoulder muscle MVC force for the involved extremity did not differ significantly as compared with the uninvolved extremity, whereas the shoulder AROM in flexion and external rotation remained lower.

Seven-month wintertime supplementation of 1200 IU vitamin D has no effect on hand grip strength in young, physically active males: A randomized, controlled study.

Background: There has been a growing interest in the role of vitamin D for the well-being and physical performance of humans under heavy training such as conscripts in military service; however, there is a lack of long-term supplementation studies performed on members of this type of young, physically active, male population. The hypothesis of the study was that vitamin D supplementation during wintertime will decrease the prevalence of critically low vitamin D blood serum levels and increase hand grip strength during the winter season among young male conscripts. Study Design: Longitudinal, triple-blinded, randomized, placebo-controlled trial. Methods: Fifty-three male conscripts from the Estonian Army were randomized into two groups: 27 to an intervention group and 26 to a placebo group. The groups were comparable in terms of their demographics. The intervention group received 1200 IU (30 µg) capsules of vitamin D3, and the control group received placebo oil capsules once per day. The length of the follow-up was 7 months, from October 2016 until April 2017. Blood serum vitamin D (25(OH)D), parathyroid hormone (PTH), calcium (Ca), ionized calcium (Ca-i), testosterone and cortisol values, and hand grip strength were measured four times during the study period. Results: The mean 25(OH)D level decreased significantly in the control group to a critically low level during the study, with the lowest mean value of 22 nmol/l found in March 2017. At that time point, 65% in the control group vs 15% in the intervention group had 25(OH)D values of less than 25 nmol/l (p < 0.001). In the intervention group, the levels of 25(OH)D did not change significantly during the study period. All other blood tests revealed no significant differences at any time point. The corresponding result was found for hand grip strength at all time points. Conclusion: Long-term vitamin D supplementation during wintertime results in fewer conscripts in the Estonian Army with critically low serum vitamin D (25(OH)D) levels during the winter season. However, this did not influence their physical performance in the form of the hand grip strength test.

Relationship between postactivation potentiation of knee extensor muscles, sprinting and vertical jumping performance in professional soccer players.

Little is known about the relationship between postactivation potentiation (PAP) in human muscles, assessed by enhancement of twitch torque after a conditioning maximal voluntary contraction (MVC), and performance in activities requiring power and speed. Moreover, no studies have assessed PAP in soccer players who train power and endurance simultaneously. The purpose of the present study was to examine the relationship between twitch PAP in knee extensor (KE) muscles, and sprinting and vertical jumping performance in soccer players. Fourteen professional male soccer players with mean (SD) age 20.0 (3.6) years, height 177.9 (6.9) cm and body mass 70.5 (5.7) kg) were tested for 15-m sprint time, vertical jump height in countermovement (CMJ) and squat (SJ) jumps. PAP in KE muscles was induced by a 10-s isometric MVC. Electrically evoked twitches of KE muscles were evoked before and after the conditioning MVC. Immediately after the conditioning MVC, twitch peak torque (PT) and maximal rates of torque development and relaxation were significantly potentiated. A significant negative correlation was found between 15-m sprint time and jump height in CMJ (r = -0.63) and SJ (r = -0.57). PAP of twitch PT correlated significantly positively with jump height in CMJ (r = 0.61) and SJ (r = 0.64), and negatively with 15-m sprint time (r = -0.59). In conclusion, twitch PAP in KE muscles was significantly correlated with performance in vertical jumping and sprinting in male professional soccer players, whereas the magnitude of PAP in soccer players was similar to that observed previously in power-trained athletes.

Vitamin C and E Treatment Blocks Changes in Kynurenine Metabolism Triggered by Three Weeks of Sprint Interval Training in Recreationally Active Elderly Humans.

The kynurenine pathway (KP) is gaining attention in several clinical fields. Recent studies show that physical exercise offers a therapeutic way to improve ratios of neurotoxic to neuroprotective KP metabolites. Antioxidant supplementation can blunt beneficial responses to physical exercise. We here studied the effects of endurance training in the form of sprint interval training (SIT; three sessions of 4-6 × 30 s cycling sprints per week for three weeks) in elderly (~65 years) men exposed to either placebo (n = 9) or the antioxidants vitamin C (1 g/day) and E (235 mg/day) (n = 11). Blood samples and muscle biopsies were taken under resting conditions in association with the first (untrained state) and last (trained state) SIT sessions. In the placebo group, the blood plasma level of the neurotoxic quinolinic acid was lower (~30%) and the neuroprotective kynurenic acid to quinolinic acid ratio was higher (~50%) in the trained than in the untrained state. Moreover, muscle biopsies showed a training-induced increase in kynurenine aminotransferase (KAT) III in the placebo group. All these training effects were absent in the vitamin-treated group. In conclusion, KP metabolism was shifted towards neuroprotection after three weeks of SIT in elderly men and this shift was blocked by antioxidant treatment.

Self-Reported Knee Pain Does Not Impact Physical Training Negatively in Conscripts.

INTRODUCTION: Despite the great number of investigations on the effects of injuries during military service, there is limited information available on the use of self-reported instruments. This study evaluated self-reported knee pain (KP) and its effect on physical performance during military service in the Estonian Defense Forces. MATERIAL AND METHODS: Ninety-five male conscripts aged 19-25 years were divided into two study groups based on the occurrence of KP or not. Self-reported KP and function according to the Knee Injury and Osteoarthritis Outcome Score (KOOS) were measured. Physical fitness level was scored using the Army Physical Fitness Test (APFT). KOOS and APFT were measured in the beginning and at the end of the 6-month period of military service. RESULTS: Significant differences in favor of the group without KP (P < 0.001) were found for all subgroups of the KOOS. In spite of KP, the physical condition improved significantly (P < 0.001) in both study groups as measured with both the APFT test (22.2% increase) and running time (10.3% decrease). CONCLUSION: In conclusion, self-reported KP and limited function according to KOOS did not hinder the improvement of physical condition and running speed as assessed by APFT in Estonian conscripts.