Load magnitude affects patellar tendon mechanical properties but not collagen or collagen cross-linking after long-term strength training in older adults

Abstract

BackgroundRegular loading of tendons may counteract the negative effects of aging. However, the influence of strength training loading magnitude on tendon mechanical properties and its relation to matrix collagen content and collagen cross-linking is sparsely described in older adults. The purpose of the present study was to compare the effects of moderate or high load resistance training on tendon matrix and its mechanical properties.MethodsSeventeen women and 19 men, age 62–70 years, were recruited and randomly allocated to 12 months of heavy load resistance training (HRT), moderate load resistance training (MRT) or control (CON). Pre- and post-intervention testing comprised isometric quadriceps strength test (IsoMVC), ultrasound based testing of in vivo patellar tendon (PT) mechanical properties, MRI-based measurement of PT cross-sectional area (CSA), PT biopsies for assessment of fibril morphology, collagen content, enzymatic cross-links, and tendon fluorescence as a measure of advanced glycation end-products (AGEs).ResultsThirty three participants completed the intervention and were included in the data analysis. IsoMVC increased more after HRT (+ 21%) than MRT (+ 8%) and CON (+ 7%) (p < 0.05). Tendon stiffness (p < 0.05) and Young’s modulus (p = 0.05) were also differently affected by training load with a reduction in CON and MRT but not in HRT. PT-CSA increased equally after both MRT and HRT. Collagen content, fibril morphology, enzymatic cross-links, and tendon fluorescence were unaffected by training.ConclusionDespite equal improvements in tendon size after moderate and heavy load resistance training, only heavy. load training seemed to maintain tendon mechanical properties in old age. The effect of load magnitude on tendon biomechanics was unrelated to changes of major load bearing matrix components in the tendon core.The study is a sub-study of the LISA study, which was registered at http://clinicaltrials.gov (NCT02123641) April 25th 2014.

Effect of blood‐flow restricted vs heavy‐load strength training on muscle strength: Systematic review and meta‐analysis

“…On the other hand, a positive relation between the level of mechanical loading and bone/tendon adaptations seem to exist, suggesting that morphological and/or mechanical tendon/bone adaptations may not be highly stimulated by LL‐BFR training. In contrast, it is well‐recognized that heavy‐load training can elicit neuromotor adaptations as well as tendon and bone adaptations in both young and old individuals …”

“…In contrast, it is well-recognized that heavy-load training can elicit neuromotor adaptations as well as tendon and bone adaptations in both young and old individuals. 4,5,[63][64][65] Additionally, the relative safety of LL-BFR training has not been exhaustively investigated. Studies examining potential risk factors related to LL-BFR training (eg, blood coagulation, cardiovascular responses, oxidative stress, and muscle damage) show no additional or only minor overall effects of LL-BFR exercise/training compared to baseline and/or more traditional exercise regimes.…”

Muscle‐tendon morphology and function following long‐term exposure to repeated and strenuous mechanical loading

“…Although the morphological, cellular, and neural mechanisms of muscular adaptations have been described and explained in detail, 1,2 the literature regarding muscle‐tendon architectural adaptations has developed considerably more recently with advancements in medical imaging technology. Adaptations in human muscle‐tendon architecture, material properties, and mechanical behavior due to mechanical overloading have been observed and linked to a range of training regimens and habitual overloading, with patellar and Achilles tendons (PT, AT) and their attached muscle groups receiving most of the research attention 2‐8 . Although a primary scientific consensus regarding short to medium exposure (<20 weeks) to external overloading and its effects on knee and ankle musculotendinous structures has been gradually formulated, 2,5,6,9 the evidence on long‐term exposure is more variable.…”

The biological and psychosocial aspects of successful aging in high functional elders: A longitudinal study

“…In the fourth manuscript, Pötzelsberger et al report the stability of muscle strength, muscle architecture, and patellar tendon mechanical properties after 6‐year follow‐up. Greater intensity and volumes of physical activity may be required above 65 years of age to elicit improvements in muscle‐tendon mechanical properties . However, the fact that no deterioration was observed could also be interpreted as an anti‐aging effect of active lifestyle .…”

“…Greater intensity and volumes of physical activity may be required above 65 years of age to elicit improvements in muscletendon mechanical properties. 12 However, the fact that no deterioration was observed could also be interpreted as an anti-aging effect of active lifestyle. 13 In the last manuscript, Dela et al 14 examined the changes in cardiometabolic trajectories and VO 2 max changes.…”