To Örebro University

The role of daily time spent sedentary and in different intensities of physical activity (PA) for the maintenance of muscle health currently remains unclear. Therefore, we investigated the impact of reallocating time spent in different PA intensities on sarcopenia risk in older adults, while considering PA type (muscle strengthening activities, MSA) and protein intake. In a sample of 235 community-dwelling older adults (65-70 years), a sarcopenia risk score (SRS) was created based on muscle mass assessed by bioimpedance, together with handgrip strength and performance on the five times sit-to-stand (5-STS) test assessed by standardized procedures. Time spent in light-intensity PA (LPA), moderate-to-vigorous PA (MVPA), and being sedentary was assessed by accelerometry, and PA type (MSA) by self-report. Linear regression models based on isotemporal substitution were employed. Reallocating sedentary time to at least LPA was significantly (p < 0.05) related to a lower SRS, which remained evident after adjustment by PA type (MSA) and protein intake. Similarly, reallocating time in LPA by MVPA was related to a significantly (p < 0.05) lower SRS. Our results emphasize the importance of displacing sedentary behaviours for more active pursuits, where PA of even light intensities may alleviate age-related deteriorations of muscle health in older adults.

Ageing is accompanied by a decline in physical function, including loss of muscle mass and muscle strength, which leads to impaired ability to perform activities of daily living and loss of independence. Physical activity (PA) is currently viewed as a key lifestyle factor with potential to mitigate these age-related deteriorations. Therefore, public health organizations have issued guidelines about amounts and types of physical activity for health benefits, where reductions in daily time spent sedentary in favour of more time in aerobic-type moderate-to-vigorous PA (MVPA) are emphasized. In addition, regular engagement in musclestrengthening activities (MSA) are recommended to promote maintenance of muscle mass and strength in ageing populations. However, to what extent different amounts and types of PA impact on different indicators of physical function, including muscle mass and strength, remains currently unclear. Therefore, the overall aim of this thesis was to investigate the impact of PA behaviours on muscle mass and physical function in older adults. In study I, it was shown that regular engagement in exercise activities during middle age was associated with a significantly higher muscle mass and a better cardiorespiratory fitness at old age. In study II, replacement of daily sedentary time with PA of at least light intensity was associated with a significantly lower sarcopenia risk in older adults, with greater benefits above the moderate PA intensity. Study III revealed that engagement in MSA at least twice a week was linked to a significantly lower sarcopenia risk in older adults who already perform at least 150 weekly minutes of MVPA. Finally, study IV showed that older adults who accumulate at least 300 weekly minutes of MVPA have a significantly better overall physical function than those who accumulate at least 150 but less than 300 minutes of MVPA per week. Overall, the findings from this thesis highlight the importance of adherence to the aerobic-type MVPA guideline alongside recommended engagement in MSA for mitigating age-related decline in physical function in older adults. Notably, accumulation of MVPA time beyond the minimum recommended amount provides additional functional benefits.

Sarcopenia in older adults is associated with a higher risk of falls, disability, loss of independence, and mortality. Current physical activity (PA) guidelines recommend engagement in muscle-strengthening activities (MSA) in addition to aerobic moderate-to-vigorous physical activity (MVPA). However, little is known about the impact of MSA in addition to adherence to the MVPA recommendation in the guidelines. The aim of the present cross-sectional study was to determine whether or not engagement in MSA is linked to sarcopenia risk in older adults who meet the PA guidelines of 150 min of MVPA per week. A total of 193 community-dwelling older men and women (65-70 years) were included in the study. A continuous sex-specific clustered sarcopenia risk score (SRS) was created based on muscle mass assessed using bioelectrical impedance analysis, handgrip strength, and five times sit-to-stand (5STS) time, assessed using standardized procedures. Adherence to PA guidelines was assessed using the Actigraph GT3x accelerometer and the EPAQ2 questionnaire. Guideline adherence to MSA twice a week was related to a significantly (p < 0.05) lower SRS compared to those who did not. This finding was evident after adjustment for adherence to the protein intake guideline and abdominal obesity. Similar impacts were observed for muscle mass and 5-STS but not for handgrip strength. In conclusion, guideline adherence to MSA is related to lower sarcopenia risk in older adults who already accumulate 150 weekly minutes of MVPA, which reinforces the promotion of the MSA guideline, alongside the MVPA guideline, to fight against sarcopenia progression in ageing populations. 

BACKGROUND: The impact of regular exercise habits at middle-age on muscle mass and function at old age remains inconclusive. While regular exercise likely represents a primary source of health-enhancing physical activity (PA), the physical demand of occupation needs to be considered. Additionally, PA level at old age should be taken into account in order to elucidate true associations between past exercise behaviors and muscle mass and function at old age. Therefore, the aim of the study was to examine the impact of regular exercise habits during middle age years on muscle mass and physical function at old age, while considering occupation and objectively assessed PA level at old age.

METHODS: Self-reported leisure-time PA during middle age years [35-65 years] and present accelerometer-derived PA level were assessed in a population of community-dwelling older women (65-70 years; n = 112). Participants who accumulated at least 600 MET-min of PA per week during middle age years were classified as physically active. Skeletal muscle mass index (SMI), aerobic fitness and maximal isometric arm and leg strength were determined. Analyses of differences in muscle mass and physical function between physically active and inactive at middle age were adjusted by present PA, adiposity level, and the physical demand of former occupation (sedentary vs manual).

RESULTS: Participants accumulating at least 600 MET-min of exercise-related activities during middle-age years had higher aerobic fitness (P < 0.01) and SMI (P < 0.05) at old age compared to their less active peers. Notably, these beneficial impacts were driven by exercise habits during late middle-age period [50 to 65 years], and remained significant after further adjustment by the physical demand of former occupation and present PA behavior at old age. Finally, middle-age engagement in exercise-related activities had no influence on maximal arm and leg isometric strength at old age.

CONCLUSION: Our findings highlight the importance of engaging in regular PA of at least moderate intensity during middle age years in order to promote benefits at the level of muscle mass and aerobic fitness. This clearly supports the potential of PA in delaying aerobic capacity impairment and the occurrence of clinically manifest sarcopenia at old age.

Introduction: Healthy dietary patterns and physical activity (PA) represent important lifestyle behaviors with considerable potential to influence on age-related metabolic health. Yet, data on the combined effects of these lifestyle behaviors on metabolic health including low-grade systemic inflammation in aging populations remain scarce. Therefore, this protocol describes a randomized controlled trial aiming to examine the impacts of healthy dietary patterns alone or combined with PA on metabolic health in middle-aged and older men and women.

Material and methods: The ORUDIET study is a 3-arm randomized controlled 16-week trial: Healthy Diet (HD), Healthy diet plus PA (HD-PA), and control (CON). The trial is open label, randomized with allocation concealment, parallel groups with passive controls. Participants without overt disease aged between 55 and 70 years, with BMI below 35, a current intake of a maximum of 1 serving of fruit and vegetable per day, and noncompliance to PA guidelines are eligible for inclusion. Participants in HD are instructed to increase fruit and vegetable intake to 5 servings per day (equivalent to 500 g). Participants in HD-PA receive the same dietary intervention as the HD and are additionally instructed to engage in moderate-to-vigorous physical activities for at least 150 minutes per week. The primary study outcomes are changes in metabolic and inflammatory health biomarkers. Secondary outcomes are changes in body composition and perceived health.

Ethics and dissemination: The study protocol has been approved by the ethical review board in Uppsala, Sweden. The results will be published in peer-reviewed journals and disseminated in national and international conferences.

This study investigated the effects of the inclusion of a postactivation potentiation (PAP) specific warm-up (WU) consisting of all-out sprints on 10 kilometre cycling time trial (10 km-TT) pacing and performance. Following familiarization, thirteen well-trained male participants performed two 10 km cycle laboratory time trials following warm-ups that included either four 8 seconds (s) maximal sprints, or a matched total work performed at a constant exercise intensity. Power output (PO), heart rate (HR), and ratings of perceived exertion (RPE) were measured throughout and blood lactate (BLa) 3 minutes post exercise. There were no significant differences in total performance time, PO in any 2 km segment, RPE, or post-exercise BLa between conditions. Some significant differences (P<0.05) were observed in heart rate and cadence between 2 km segments. Addition of four all-out sprints to the WU did not improve 10 km time trial performance or alter pacing strategy displayed. This suggests that maximal sprinting in a warming up might not be an effective strategy to improve cycling time trial endurance performance.