The aim of this study was to monitor the long-term effects of skiing on health-related parameters and implant related factors like loosening and wear in patients with total knee arthroplasty. This paper describes the overall study design, general demographics, and physiological demand of the intervention phase. A control group design consisting of an intervention group (n = 14; age: 70.4 ± 4.5 years) and a control group (n = 17; age: 71.5 ± 5.1 years) was utilized in this study. Parameters of interest were measured during pre-, post-, and retention test sessions. During the 12 weeks of intervention, an average of 25.5 days of guided skiing was conducted by each patient. Daily heart rate (HR) profiles and global positioning system data throughout the ski day were recorded. The intervention group completed an average of 3393 vertical meters of downhill skiing, with a total skiing distance of 33.6 km/day. Average skiing speed was 8.2 m/s. In the skiing phase, the average physiological load was 75.9 ± 6.6% of HRmax . Further effects of the 12-week skiing intervention on the tested parameters will be reported in the following papers of this supplementum.

This study focused on the psychological and quality of life aspects of resuming alpine skiing practice after total knee arthroplasty (TKA) in elderly skilled skiers. Two data pools were used in order to analyze psychological states: (a) at the beginning, at the end, and 8 weeks after a 12-week skiing intervention; and (b) concerning diurnal variations of states (i.e., skiing days compared with everyday life during intervention and retention phase). In particular, effects of skiing on amount of physical activity and perceived exertion, perceived pain and knee function, and subjective well-being were analyzed using a control group design. Results reveal that the skiing intervention substantially increases the amount of physical activity by the intervention group (122.30 ± 32.38 min/day), compared with the control group (75.14 ± 21.27 min/day) [F (2, 32) = 8.22, P < 0.01, η(2)  = 0.34)]. Additionally, the analyses of psychological states demonstrated that skiing goes along with enhanced well-being and no significant impact on perceived pain, exertion or knee function. In sum, alpine skiing can be recommended for older persons with TKA with respect to well-being, perceived pain and knee function, and perceived exertion.

This article aims to (a) describe the study design of a 6‐year follow‐up multidisciplinary research project on aging, (b) report the psychosocial characteristics of the sample in detail, and (c) evaluate aging‐related changes of health, physical activity, and psychosocial characteristics in 10 young‐old (age at pre‐test: M ± SD = 63.2 ± 1.5) and 12 old‐old (age at pre‐test: M ± SD = 69 ± 2) individuals. Both age groups consist of individuals displaying a high health status, a high extent of physical activity, high levels of psychosocial properties in the dimensions of well‐being, life satisfaction, self‐concept, body image, self‐esteem, and self‐efficacy, as well as a low general depression index. Psychosocial characteristics demonstrated a stable pattern over a period of nearly 6 years in both age groups with the exceptions of physical activity, satisfaction with children, general depression, and self‐efficacy. Furthermore, physical self‐concept decreased in old‐old adults, whereas the young‐olds showed no change. We assume that a high psychosocial status and a physically active lifestyle play an important role for mastering aging successfully in two life phases, each of which has its own challenges for older individuals. The decline in the physical self‐concept of old‐olds is interpreted as a first sign of subjective aging. Its association with losses in physical performance should be addressed in future studies. Finally, aging‐related changes should be monitored on an individual level in order to capture the complex dynamic of aging that is not considered in analyses of between‐person differences or averages.

This study investigated the effect of a 12-week recreational skiing intervention on lower limb muscle strength and cardiorespiratory fitness in participants with unilateral total knee arthroplasty (TKA). Twenty-seven older adults (70 ± 5 years) were assigned to the intervention (n = 13) or control group (n = 14) after surgery (2.5 ± 1 years). Leg muscle strength was measured using an IsoMed 2000 dynamometer and cardiorespiratory fitness was determined by cycle ergometry before and after the intervention as well as after an 8-week retention period. The skiing intervention led to increased muscle strength in the operated leg during unilateral single joint isometric extension (maximal force: 11%; P < 0.05; rate of torque development: 24%; P < 0.05) and during the unilateral multi-joint isokinetic single leg strength test (8%; P < 0.05). This resulted in a decreased asymmetry index in the isokinetic test (13% to 5%; P < 0.05). These adaptations remained unchanged toward the retention test. No effect was observed for cardiorespiratory fitness. The results demonstrate that muscle contraction forces required during recreational skiing in individuals with TKA seem adequate and effective to increase quadriceps and hamstrings muscle strength in the initially weaker operated leg and to reduce an augmented post-operative asymmetry index.

The aim of the study was to assess the effect of a recreational alpine skiing intervention on implant-related factors, such as loosening and wear, in patients with total knee arthoplasty (TKA). A group of 16 TKA patients were examined 2.3 ± 0.1 years after skiing about 80 days over three seasons inclusive of a ski intervention of 2-3 times per week (25.5 days) over a 12-week period. Mean follow-up period was 5.1 ± 1 years after surgery. All patients had excellent clinical and radiological outcomes. The average flexion was 120-130°, the average Oxford Knee Score increased from 15 points pre-operatively to 47.4 points post-operatively. An average Tegner activity level of 5.5 was assessed, indicating a very high post-operative activity level. No radiolucencies or osteolyses were observed in any of the radiographs. One patient sustained a meniscal tear in the contralateral knee. Recreational alpine skiing on intermediate terrain at moderate speed can be recommended after TKA. Analysis of mid-term follow-up has not shown any negative effect on the implant loosening or additional polyethylene wear.

The aim of the study was to examine the effect of a 12-week recreational skiing intervention on functional gait performance in people with unilateral total knee arthroplasty (TKA). Twenty-three older adults (71 ± 5 years) were assigned to the intervention (IG) or control group (CG). Test time and ground reaction forces (GRF) were recorded at pre- and post-intervention and in the retention phase during functional gait tests. Ground contact was recorded bilaterally and divided into the weight acceptance and push-off phases. In IG, a faster stair descent time (16%) was observed at post-test with no further change at the retention test. The asymmetry indices for all analyzed variables were decreased in stair descent and during weight acceptance in stair ascent and level walking without further changes between post- and retention test. The reduced asymmetries occurred mainly because of increased loading of the operated leg. Most variables were unchanged in CG. Similar to the force data, the asymmetry index for temporal stride characteristics was reduced in all stair descent variables. These results demonstrate that alpine skiing as a leisure-time activity has a beneficial effect on gait performance and leads to a more balanced load distribution between the legs during daily activities.

We investigated the effect of alpine skiing for 12 weeks on skeletal muscle characteristics and biomarkers of glucose homeostasis and cardiovascular risk factors. Twenty-three patients with a total knee arthroplasty (TKA) were studied 2.9 ± 0.9 years (mean ± SD) after the operation. Fourteen patients participated in the intervention group (IG) and nine in the control group (CG). Blood samples and muscle biopsies were obtained before (PRE) and 7.3 ± 0.8 days after (POST) the intervention, and blood samples again after a retention (RET) phase of 8 weeks. With skiing, glucose homeostasis improved in IG (decrease in fasting insulin, increase in muscle glycogen) but not in CG. Fiber type distribution and size, as well as capillary density and number of capillaries around the fibers (CAF), were not different between the operated and the non-operated leg in either group. The relative number of type I fibers increased with skiing in IG with no change in CG. Inflammatory biomarkers, plasma lipids, and mitochondrial proteins and activity did not change. Alpine skiing is metabolically beneficial and can be used as a training modality by elderly people with TKA.

The aim of this pilot study was to determine the pressure distribution, symmetry of load between operated (OP) and non-operated (NOP) leg, and pain level during alpine skiing in participants with unilateral total knee arthroplasty (TKA). The responses of the dependent variables were analyzed following a 10-week guided skiing intervention of 2-3 days of skiing per week. Ground reaction force (GRF) was recorded bilaterally and was determined for 13 participants with TKA (65 ± 4 years) at pre- and post-test. Additionally, pain perception was determined using a numeric rating scale in the OP leg at both test sessions and after each skiing day. No statistical differences were observed between OP and NOP legs for peak and average GRF as well as the asymmetry indices at pre-test. Pain perception was low and was not increased as a consequence of the skiing intervention. In conclusion, alpine skiing did not lead to increased or decreased loading of the OP leg compared with the NOP leg. Therefore, alpine skiing may be allowed for patients with skiing experience and a good clinical outcome.