Evelien Van Roie

Strength training at high versus low external resistance in older adults: Effects on muscle volume, muscle strength, and force–velocity characteristics

Muscle adaptations can be induced by high-resistance exercise. Despite being potentially more suitable for older adults, low-resistance exercise protocols have been less investigated. We compared the effects of high- and low-resistance training on muscle volume, muscle strength, and force-velocity characteristics. Fifty-six older adults were randomly assigned to 12 weeks of leg press and leg extension training at either HIGH (2×10-15 repetitions at 80% of one repetition maximum (1RM)), LOW (1×80-100 repetitions at 20% of 1RM), or LOW+ (1×60 repetitions at 20% of 1RM, followed by 1×10-20 repetitions at 40% of 1RM). All protocols ended with muscle failure. Leg press and leg extension of 1RM were measured at baseline and post intervention and before the first training session in weeks 5 and 9. At baseline and post intervention, muscle volume (MV) was measured by CT-scan. A Biodex dynamometer evaluated knee extensor static peak torque in different knee angles (PT(stat90°), PT(stat120°), PT(stat150°)), dynamic peak torque at different speeds (PT(dyn60°s)(-1), PT(dyn180°s)(-1), PT(dyn240°s)(-1)), and speed of movement at 20% (S20), 40% (S40), and 60% (S60) of PTstat90°. HIGH and LOW+ resulted in greater improvements in 1RM strength than LOW (p<0.05). These differences were already apparent after week 5. Similar gains were found between groups in MV, PT(stat), PT(dyn60°s)(-1), and PT(dyn180°s)(-1). No changes were reported in speed of movement. HIGH tended to improve PT(dyn240°s)(-1) more than LOW or LOW+ (p=0.064). In conclusion, high- and low-resistance exercises ending with muscle failure may be similarly effective for hypertrophy. High-resistance training led to a higher increase in 1RM strength than low-resistance training (20% of 1RM), but this difference disappeared when using a mixed low-resistance protocol in which the resistance was intensified within a single exercise set (40% of 1RM). Our findings support the need for more research on low-resistance programs in older age, in particular long-term training studies and studies focusing on residual effects after training cessation.

Force-Velocity Characteristics of the Knee Extensors: An Indication of the Risk for Physical Frailty in Elderly Women

OBJECTIVES To examine the relationship between muscle strength, speed of movement, muscle mass (MM), and functional performance in elderly women and to determine optimal threshold values below which physical frailty occurs. DESIGN Survey. SETTING University-based laboratory. PARTICIPANTS Institutionalized women (N=123; mean age, 79.67 ± 5.2y). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Force-velocity characteristics of the knee extensors were evaluated by using isometric, isokinetic, and ballistic tests on a motor-driven dynamometer. Isometric (ISOM) strength, dynamic strength, maximal speed of movement (SoM, unloaded), and speed of movement with standardized resistance of 20% (S(20)), 40% (S(40)), and 60% (S(60)) of the isometric maximum were recorded. MM of the upper leg was determined by using computed tomography. The modified Physical Performance Test (mPPT) was used to assess functional performance. RESULTS Force-velocity characteristics (r varied from .31-.68) and MM (r=.41) correlated significantly with functional performance (P<.05). In a forward stepwise regression model, only SoM and ISOM strength remained independently associated with mPPT score (R(2)=.49), with SoM accounting for most of the variance. The threshold value that optimally differentiates between women with mild (mPPT score, 25-31) or without (mPPT score ≥32) physical frailty was 350°/s for SoM and 1.46N m/kg for ISOM strength. Sensitivity and specificity ranged from 74% to 77% and 71% to 77%, respectively. CONCLUSIONS SoM is a key component in the onset of functional difficulties in elderly women. Exercise interventions specifically targeting muscle power (by including exercises at high velocities) thus might be crucial to prevent functional decline.

Long-Term Impact of Strength Training on Muscle Strength Characteristics in Older Adults

OBJECTIVE To evaluate the long-term preventive impact of strength training on muscle performance in older adults. DESIGN A 7-year follow-up on a 1-year randomized controlled trial comparing the effects of combined resistance training and aerobic training and whole-body vibration training on muscle performance. SETTING University training center. PARTICIPANTS Men and women (N=83; control [CON] group, n=27; strength-training intervention [INT] group, n=56) between 60 and 80 years of age. INTERVENTIONS The INT group exercised 3 times weekly during 1 year, performing a combined resistance training and aerobic training program or a whole-body vibration training program. The former training program was designed according to American College of Sports Medicine guidelines. The whole-body vibration training program included unloaded static and dynamic leg exercises on a vibration platform. The CON group did not participate in any training program. MAIN OUTCOME MEASURES Static strength (STAT), dynamic strength at 60°/s (DYN60) and at 240°/s (DYN240), speed of movement at 20% (S20). RESULTS From baseline to postintervention, muscle performance did not change in the CON group, except for S20 (+6.55%±2.88%, P<.001). One year of strength training increased (P≤.001) STAT (+11.46%±1.86%), DYN60 (+6.96%±1.65%), DYN240 (+9.25%±1.68%), and S20 (+7.73%±2.19%) in the INT group. Between baseline and follow-up, muscle performance decreased (P<.001) in both groups. However, STAT and DYN60 showed a significantly lower loss in the INT group (-8.65%±2.35% and -7.10%±2.38%, respectively) compared with the CON group (-16.47%±2.69% and -15.08%±2.27%, respectively). This positive impact might be due to the preservation of the training-induced gains, given the similar annual decline rates in both groups from postintervention to follow-up. Additionally, in trained participants, aging seems to impact velocity-dependent strength and power more compared with basic strength, as the total losses in DYN240 (CON, -15.93%±2.64%; INT, -11.39%±1.95%) and S20 (CON, -14.39%±2.10%; INT, -13.16%±1.72%) did not differ significantly between the groups. CONCLUSIONS A 1-year strength-training intervention results in an improved muscle performance in older adults 7 years after their enrollment in the intervention. However, an extensive exercise program cannot attenuate the age-related decline once the intervention stops.

Dose-and gender-specific effects of resistance training on circulating levels of brain derived neurotrophic factor (BDNF) in community-dwelling older adults.

BACKGROUND BDNF is known to induce neuroplasticity and low circulating levels have been related to neuronal loss in older persons. Physical exercise is thought to trigger BDNF-induced neuroplasticity, but conflicting observations have been reported regarding the effects of resistance training on circulating BDNF in the elderly. These conflicting observations might reflect dose-and gender-specific differences. METHOD Fifty-six apparently healthy elderly (68 ± 5 years) participants were randomized to 12 weeks of resistance training (3×/week) at either high-resistance (HIGH, 8 Males, 10 Females, 2 × 10-15 repetitions at 80% 1 RM), low-resistance (LOW, 9 Males, 10 Females, 1 × 80-100 repetitions at 20% 1 RM), or mixed low-resistance (LOW+, 9 Males, 10 Females, 1 × 60 repetitions at 20% 1 RM followed by 1 × 10-20 repetitions at 40% 1 RM). Serum was collected for BDNF assay at baseline and after 12 weeks (24 h-48 h after the last training). RESULTS 12 weeks of LOW+ exercise significantly increased BDNF levels in male (from 34.9 ± 10.7 ng/mL to 42.9 ± 11.9 ng/mL, time × group interaction p=0.013), but not in female participants. No significant change was observed in HIGH or LOW, neither in male nor female subjects. CONCLUSION Our results show that only the mixed-low-resistance training program with a very high number of repetitions at a sufficiently high external resistance was able to increase circulating BDNF in older male participants. Training to volitional fatigue might be necessary to obtain optimal results. Additional studies are needed to unravel the underlying mechanisms, as well as to confirm the observed gender difference.

Is knee extension strength a better predictor of functional performance than handgrip strength among older adults in three different settings

BACKGROUND The first purpose was to examine whether knee extension strength is a better predictor of functional performance than handgrip strength among older adults (≥60 years). The second purpose was to identify functionally relevant cut-off values for muscle strength. METHODS 770 community-dwelling older adults, 104 older adults living in assisted living facilities and 73 nursing home residents were included. Static strength, expressed in kg/kg body weight (BW), was measured using two field tests: handgrip (GRIP/BW) and knee extension (KNEE/BW) test. Functional performance was assessed with 6-Minute Walk Distance (6MWD, N=947) and modified Physical Performance Test (mPPT, N=152). RESULTS Both GRIP/BW and KNEE/BW were positively correlated with functional performance in all settings (p<0.05). In the community and nursing homes, both strength variables equally contributed to functional performance. In assisted living facilities, KNEE/BW (R(2)6MWD=0.39 and R2mPPT=0.35) was clearly a better predictor of functional performance than GRIP/BW (R(2)6MWD=0.15 and R2mPPT=0.12). GRIP/BW had no added value to KNEE/BW in order to explain the variance in functional performance. Functionally relevant cut-off values for static strength, for men and women respectively, were set at 0.40 and 0.31 for KNEE/BW and at 0.43 and 0.31 for GRIP/BW. CONCLUSIONS Handgrip and knee extension strength are both important predictors of functional performance in older adults. In assisted living facilities only, knee extension strength was clearly more predictive than handgrip strength. Both cut-off values appear to be highly sensitive to screen for functionally relevant muscle weakness in older adults.

Low- and High-Resistance Exercise: Long-Term Adherence and Motivation among Older Adults

Background: In terms of motivation and long-term adherence, low-resistance exercise might be more suitable for older adults than high-resistance exercise. However, more data are needed to support this claim. Objective: The objective was to investigate the effect of low- and high-resistance exercise protocols on long-term adherence and motivation. Methods: This study was designed as an exploratory 24-week follow-up of a randomized 12-week resistance training intervention in older adults. Participants were free to decide whether or not they continued resistance training at their own expense following the intervention. Fifty-six older adults were randomly assigned to HIGH [2 × 10-15 repetitions at 80% of one repetition maximum (1RM)], LOW (1 × 80-100 repetitions at 20% of 1RM), or LOW+ (1 × 60 repetitions at 20% of 1RM + 1 × 10-20 repetitions at 40% 1RM). Motivation, self-efficacy and the perceived barriers for continuing resistance exercise were measured after cessation of each supervised intervention and at follow-up, while long-term adherence was probed retrospectively at follow-up. Results: Participants reported high levels of self-determined motivation before, during, and after the supervised intervention, with no differences between groups (p > 0.05). Nevertheless, only few participants continued strength training after the intervention: 17% in HIGH, 21% in LOW+, and 11% in LOW (p > 0.05). The most commonly reported barriers for continuing resistance exercise were perceived lack of time (46%), being more interested in other physical activities (40%), seasonal reasons (40%), and financial cost (28%). Conclusion: The results suggest no difference in long-term adherence after the end of a supervised exercise intervention at high or low external resistances. Long-term adherence was limited despite high levels of self-determined motivation during the interventions. These findings highlight the importance of further research on developing strategies to overcome barriers of older adults to adhere to resistance exercise without supervision.

Impact of External Resistance and Maximal Effort on Force-Velocity Characteristics of the Knee Extensors during Strengthening Exercise: a Randomized Controlled Experiment

Abstract Van Roie, E, Bautmans, I, Boonen, S, Coudyzer, W, Kennis, E, and Delecluse, C. Impact of external resistance and maximal effort on force-velocity characteristics of the knee extensors during strengthening exercise: A randomized controlled experiment. J Strength Cond Res 27(4): 1118–1127, 2013—It remains controversial whether maximal effort attained by high external resistance is required to optimize muscle adaptation to strengthening exercise. Here, we compared different training protocols reaching maximal effort with either high-resistance (HImax, 80% of 1-repetition maximum [1RM]) or low-resistance (LOmax, ⩽40% 1RM). Thirty-six young volunteers were randomly assigned to 9 weeks of leg extension training at either HImax (1 set of 10–12 repetitions at 80% 1RM), LO (1 set of 10–12 repetitions at 40% 1RM, no maximal effort), or LOmax (1 set of 10–12 repetitions at 40% 1RM, preceded [no rest] by 60 repetitions at 20–25% 1RM). Knee extension 1RM was measured preintervention and postintervention and before the 7th, 13th, and 19th training sessions. Preintervention and postintervention, knee extensor static (PTstat) and dynamic (PTdyn) peak torque, maximal work (MW), and speed of movement at 20% (S20), 40% (S40), and 60% (S60) of PTstat were recorded with a Biodex dynamometer. All the groups showed a significant increase in 1RM, with a greater improvement in HImax from the 13th session on (p < 0.05). The HImax was the only group that significantly increased PTstat (+7.4 ± 8.1%, p = 0.01). The LOmax showed a significantly greater increase in S20 (+6.0 ± 3.2%), PTdyn (+9.8 ± 5.6%), and MW (+15.1 ± 10.6%) than both HImax and LO (p = 0.044 for S20, p = 0.030 for PTdyn, p = 0.025 for MW) and was the only group that increased in S40 (+7.7 ± 9.7%, p = 0.032). In conclusion, significant differences between HImax and LOmax on force-velocity characteristics of the knee extensors were found, although maximal effort was achieved in both training regimens. Thus, LOmax may not be considered as a replacement for HImax but rather as an alternative with different training-specific adaptations.

Effects of resistance training at different loads on inflammatory markers in young adults

PurposeSuppressing inflammaging at an early stage in life via exercise might prevent chronic diseases later in life. The aim was to investigate the influence of resistance training at different external loads on inflammatory markers in healthy young adults.MethodsSerum was collected for basal levels of cytokines (IL-1beta, IL-6, IL-8, sTNFR1, IL-1RA, IL-10 and GM-CSF) before and after 9 weeks exercise from 36 young (22 ± 2 years) healthy subjects who were randomized to three times weekly supervised resistance training at either HImax (n = 12, 1 × 10–12 repetitions at 80% 1RM), LO (n = 12, 1 × 10–12 repetitions at 40% 1RM), or LOmax (n = 12, 1 × 10–12 repetitions at 40% 1RM preceded by 60 repetitions at 20–25% 1RM) respectively.ResultsOverall, IL-8 increased (p < 0.001) and IL-6 decreased (p = 0.001) after training, but no significant time*group interaction was found (respectively, p = 0.283 and p = 0.058 for IL-8 and IL-6). When analyzed separately, IL-8 increased significantly in HImax (p = 0.022) and LOmax (p = 0.024); and IL-6 decreased significantly in LOmax (p = 0.009) and LO (p = 0.013). No significant overall time effect was observed for sTNFR1 and IL-1RA; however, in HImax sTNFR1 (p = 0.031) and IL-1RA (p = 0.014) increased significantly, but remained unchanged in LOmax and LO. IL-1beta, IL-10 and GM-CSF levels remained undetectable in most participants.ConclusionsNine weeks of resistance training—irrespective of the external load—have beneficial effects on circulating IL-8 and IL-6. In addition, training at high external load increases the anti-inflammatory cytokines sTNFR1 and IL-1RA. The results of this study show that resistance training has anti-inflammatory effects in healthy young persons and that the response of the different inflammatory mediators depends on the magnitude of the external load.

Training load does not affect detraining's effect on muscle volume, muscle strength and functional capacity among older adults

ABSTRACT Research underlines the potential of low‐load resistance exercise in older adults. However, while the effects of detraining from high‐load protocols have been established, it is not known whether gains from low‐load training would be better/worse maintained. The current study evaluated the effects of 24 weeks of detraining that followed 12 weeks of high‐ and low‐load resistance exercise in older adults. Fifty‐six older adults (68.0 ± 5.0 years) were randomly assigned to leg press and leg extension training at either HIGH load (2 × 10–15 repetitions at 80% of one‐repetition maximum (1‐RM)), LOW load (1 × 80–100 repetitions at 20% of 1‐RM), or LOW+ load (1 × 60 repetitions at 20% of 1‐RM, immediately followed by 1 × 10–20 repetitions at 40% 1‐RM). All protocols ended with volitional fatigue. The main outcome measures included mid‐thigh muscle volume, leg press 1‐RM, leg extension isometric and isokinetic strength, and functional performance. Tests were performed at baseline, post‐intervention and after 24 weeks of detraining. Results show no effect of load on preservation of muscle volume, which returned to baseline after detraining. Training‐induced gains in functional capacity and isometric strength were maintained, independent of load. HIGH and LOW+ were more beneficial than LOW for long‐lasting gains in training‐specific 1‐RM. To conclude, gains in muscle volume are reversed after 24 weeks of detraining, independent of load. This emphasises the need for long‐term resistance exercise adherence. The magnitude of detraining in neuromuscular and functional adaptations was similar between groups. These findings underline the value of low‐load resistance exercise in older age. Clinical Trial Registration NCT01707017. HighlightsHypertrophy is reversed after 24 weeks of detraining, independent of training load.Prior load does not affect decline rates in muscle strength caused by detraining.Training‐induced gains in functional capacity are maintained for a long time.Sufficient loading in resistance exercise is beneficial for long‐term 1‐RM gains.

Age-related differences in rate of power development exceed differences in peak power

Abstract Peak power (pP) declines during aging, resulting in reduced functional performance. However, the rate of power development (RPD) takes into account the short response times available during many functional tasks and may therefore add valuable information to functional declines. This study examined the age‐related effects on pP and RPD of the knee‐extensors across different loads and how these are related to functional performance. 36 young (♂21, ♀15, age = 22 ± 2 years) and 56 older adults (♂26, ♀30, age = 68 ± 5 years) performed four maximal isotonic contractions against three loads (40, 20 and 60% of maximal isometric strength) on a Biodex System 3 dynamometer. pP was calculated as the highest value and RPD as the linear slope of the power‐time curve. Functional performance in the older group was tested by 7.5‐meter fast walk, timed up‐and‐go and stair climbing. pP and RPD were higher in young compared to old and this was more pronounced with lower loads. Age‐related differences in RPD (range from 37 to 44% across loads) were higher than in pP (24–37%). Both pP and RPD showed a positive correlation with functional performance (r: 0.59–0.64). To conclude, percent differences in RPD exceed differences in pP between young and old. This emphasizes the inability to generate power rapidly at older age and underlines the importance of time‐dependent measures to detect age‐related changes in muscle function. HighlightsThe effect of aging on rate of power development is larger than on peak power.Age‐related differences in power and velocity increase as the load decreases.Rate of power development and peak power are functionally relevant in older adults.