Eivind Wang

Effective training for patients with intermittent claudication

Objective. Current guidelines for treatment of intermittent claudication (IC) do not include a specific recommendation for the intensity of exercise therapy. Thus, the purpose of this study was to determine the relative effectiveness of high versus low intensity exercise for patients with IC, and further to study the effect of such training on blood flow to the legs during exercise. Design. The effect of eight weeks of supervised endurance training was examined in 16 patients with IC. The patients were randomly assigned to training at intensities corresponding to either 60% or 80% of their peak oxygen consumption (VO2peak), respectively. Results. VO2peak and time to exhaustion increased significantly (9% and 16%, respectively) more in the high intensity group (p<0.05). Blood flow to the legs did not change after training in any of the groups. Conclusion. High intensity training gave larger improvements in VO2peak and time to exhaustion than low intensity training. As blood flow did not change after the exercise program, it is likely that the observed different increase of VO2peak was due to changed mitochondrial oxidative capacity and/or skeletal muscle diffusive capacity.

Maximal strength training improves walking performance in peripheral arterial disease patients.

Peripheral arterial disease (PAD) patients have reduced muscle strength and impaired walking ability. The aim of this study was to examine the effects of maximal strength training (MST) on walking economy and walking performance in PAD patients. Ten patients with mild to moderate‐severe claudication, classified as Fontaine stage II PAD and with functional limitations from intermittent claudication were recruited and went through an 8‐week control period followed by an 8‐week, three times a week, MST period. The patients performed four sets of five repetitions dynamic leg press with emphasis on maximal mobilization of force in the concentric action and with a progressive adjusted intensity corresponding to 85–90% of one repetition maximum (1 RM). After the MST period, leg press 1 RM significantly increased by 35.0±10.8 kg (31.3%). Dynamic rate of force development, measured on a force plate installed on the leg press, increased by 1424±1217 N/s (102.7%). The strength improvements led to a significant increase in walking economy of 9.7% when walking horizontally, and to a significant increase in walking performance of 13.6% measured on an incremental treadmill test to exhaustion. No changes were apparent after the control period. No changes in body mass or peak oxygen uptake were observed. MST increases strength in Fontaine stage II PAD patients and leads to improved walking economy. These results suggest that application of MST could accompany aerobic endurance training as a part of the treatment of PAD patients with mild to moderate‐severe claudication.

Stroke Volume Does not Plateau in Female Endurance Athletes

It has been a long-lasting debate whether the hearts stroke volume (SV) increases at high aerobic intensities or plateau. Further, sex and level of aerobic power are shown to influence the response. The purpose of this study was to investigate the SV at increasing intensities in elite female athletes and moderately trained females. 13 elite athletes and 11 moderately trained controls with maximal oxygen consumption (VO(2max)) of 67.1 ± 6.1 and 49.5 ± 2.3 mL ∙ min (- 1) ∙ kg (- 1), respectively, were recruited. SV was measured at rest, and running on a treadmill at 40%, 60%, 80% and 100% of VO(2max) using the single breath acetylene uptake (SB) technique. Both groups showed a significant (p<0.05) increase in SV from 40% of VO2max to VO(2max), with increases from 105.3 ± 19.0 to 129.1 ± 16.3 mL∙ beat(-1) for the elite females and from 68.7 ± 21.7 to 82.7 ± 14.0 mL ∙ beat (- 1) for the moderately trained. No differences were observed between groups in these increases, but the elite athletes displayed a larger (p<0.05) SV at all intensities. It is concluded that the SV increases at high aerobic intensities both in elite athlete females and moderately trained females.

High-Intensity Interval Training in Patients with Substance Use Disorder

Patients with substance use disorder (SUD) suffer a higher risk of cardiovascular disease and other lifestyle diseases compared to the general population. High intensity training has been shown to effectively reduce this risk, and therefore we aimed to examine the feasibility and effect of such training in SUD patients in clinical treatment in the present study. 17 males and 7 females (32 ± 8 yr) in treatment were randomized to either a training group (TG), treadmill interval training in 4 × 4 minutes at 90–95% of maximal heart rate, 3 days a week for 8 weeks, or a conventional rehabilitation control group (CG). Baseline values for both groups combined at inclusion were 44 ± 8 (males) and 34 ± 9 (females) mL · min−1 · kg−1, respectively. 9/12 and 7/12 patients completed the TG and CG, respectively. Only the TG significantly improved (15 ± 7%) their maximal oxygen consumption (VO2max), from 42.3 ± 7.2 mL · min−1 · kg−1 at pretest to 48.7 ± 9.2 mL · min−1 · kg−1 at posttest. No between-group differences were observed in work economy, and level of insomnia (ISI) or anxiety and depression (HAD), but a significant within-group improvement in depression was apparent for the TG. High intensity training was feasible for SUD patients in treatment. This training form should be implemented as a part of the rehabilitation since it, in contrast to the conventional treatment, represents a risk reduction for cardiovascular disease and premature death.

Concurrent strength and endurance training improves physical capacity in patients with peripheral arterial disease.

Peripheral arterial disease (PAD) patients suffer from reduced blood flow to the lower extremities, which causes impaired walking ability. Plantar flexion (PF) endurance training and maximal strength training (MST) induce distinct types of improvements in walking ability in PAD. However, the combined effects of both exercises are still not explored in these patients. This study examined whether concurrent MST and PF training would induce similar training responses as each training mode alone. Ten patients with PAD underwent 8 weeks of concurrent leg press MST and PF training, three times a week. The reference group (n=10) received recommended exercise guidelines. The training group improved treadmill peak oxygen consumption and incremental protocol time to exhaustion with 12.7 ± 7.7% and 12.6 ± 13.2%. Leg press maximal strength and rate of force development improved with 38.3 ± 3.1% and 140.1 ± 40.3%, respectively, along with a 5.2 ± 6.2% within group work economy improvement. No changes appeared in the reference group. Compared with previous studies, concurrent MST and PF training appear to induce similar training responses in PAD patients as when each training mode is executed alone, and without any adverse effects.

Impact of maximal strength training on work efficiency and muscle fiber type in the elderly: Implications for physical function and fall prevention

ABSTRACT Although aging is typically associated with a decreased efficiency of locomotion, somewhat surprisingly, there is also a reduction in the proportion of less efficient fast‐twitch Type II skeletal muscle fibers and subsequently a greater propensity for falls. Maximal strength training (MST), with an emphasis on velocity in the concentric phase, improves maximal strength, the rate of force development (RFD), and work efficiency, but the impact on muscle morphology in the elderly is unknown. Therefore we evaluated force production, walking work efficiency, and muscle morphology in 11 old (72 ± 3 years) subjects before and after MST of the legs. Additionally, for reference, the MST‐induced morphometric changes were compared with 7 old (74 ± 6 years) subjects who performed conventional strength training (CST), with focus on hypertrophy, as well as 13 young (24 ± 2 years) controls. As expected, MST in the old improved maximal strength (68%), RFD (48%), and work efficiency (12%), restoring each to a level similar to the young. However, of importance, these MST‐induced functional changes were accompanied by a significant increase in the size (66%) and shift toward a larger percentage (56%) of Type II skeletal muscle fibers, mirroring the adaptations in the hypertrophy trained old subjects, with muscle composition now being similar to the young. In conclusion, MST can increase both work efficiency and Type II skeletal muscle fiber size and percentage in the elderly, supporting the potential role of MST as a countermeasure to maintain both physical function and fall prevention in this population. HighlightsHigh intensity maximal strength training (MST) improves work efficiency.In the current study we provide new insight in the underlying muscle morphology.Despite associated with neural adaptations, MST leads to Type II fiber alterations.Similar to moderate intensity hypertrophy‐inducing strength trainingMST is an excellent strategy for improving physical function and preventing falls.

The effect of age on the v˙o2max response to high-intensity interval training

Purpose High-intensity interval training (HIIT) is documented to yield effective improvements in the cardiovascular system and be an excellent strategy for healthy aging. However, it is not determined how age may affect the training response of key components of aerobic endurance. Methods We recruited 72 males (mean ± SD, weight = 84.9 ± 12.9 kg, height = 180.4 ± 5.8 cm) and 22 females (weight = 76.0 ± 17.2 kg, height = 171.2 ± 6.7 cm) from 20 to 70+ yr with a training status typical for their age group and divided them into six decade cohorts. The participants followed supervised training with a targeted intensity of 90%–95% of maximal HR (HRmax) three times a week for 8 wk. Results After HIIT, all age groups increased (P < 0.001–P = 0.004) maximal oxygen consumption (V˙O2max) with 0.39 ± 0.20 (20–29 yr), 0.28 ± 0.21 (30–39 yr), 0.36 ± 0.08 (40–49 yr), 0.34 ± 0.27 (50–59 yr), 0.33 ± 0.23 (60–69 yr), and 0.34 ± 0.14 (70+ yr) L·min−1, respectively. These 9%–13% improvements were not significantly different between the age groups. In contrast to age, the percentage improvements after HIIT were inversely associated with baseline training status (r = 0.66, P < 0.001). HRmax was not altered within the respective age cohorts, but the two oldest cohorts exhibited a tendency (P = 0.07) to increase HRmax in contrast to a training-induced decrease in the younger cohorts. Conclusion In healthy individuals with an aerobic capacity typical for what is observed in the population, the training response is likely not affected by age in a short-term training intervention but may rather be affected by the initial training status. These findings imply that individuals across age all have a great potential for cardiovascular improvements, and that HIIT may be used as an excellent strategy for healthy aging.

Increased Blood Lactate Level Deteriorates Running Economy in World Class Endurance Athletes.

Abstract Hoff, J, Støren, Ø, Finstad, A, Wang, E, and Helgerud, J. Increased blood lactate level deteriorates running economy in world class endurance athletes. J Strength Cond Res 30(5): 1373–1378, 2016—Blood lactate accumulation is associated with development of muscle fatigue and negatively correlated to endurance performance. No research has quantified the effects of lactate presence at moderate levels of lactate accumulation. The purpose of this study was to test whether 2 moderate blood lactate concentration levels affect running economy (RE) when running at the individual lactate threshold (LT). Seven male world class endurance athletes with an average V[Combining Dot Above]O2max of 80.7 ± 2.7 ml·kg−1·min−1 or 5.8 ± 0.5 L·min−1 participated in this study. After the V[Combining Dot Above]O2max test, the subjects were resting or walking and in a random order tested for RE at their LT velocity when the blood lactate level reached either 3 mmol·L−1 or 5 mmol·L−1. After a new 5-minute exercising period at maximal aerobic velocity, the crossover lactate value RE testing was performed. Running economy was significantly (p ⩽ 0.05) deteriorated from 0.668 ± 0.044 to 0.705 ± 0.056 ml·kg−0.75·m−1 or 5.5% (p ⩽ 0.05) for blood lactate level of 3 mmol·L−1 compared with 5 mmol·L−1, respectively. Increased lactate level from 3 to 5 mmol·L−1 is thus accompanied by deteriorated RE at LT running velocity. The deteriorated RE at moderate levels of lactate concentration emphasizes the importance of avoiding intensities above LT in the early parts of a dominantly aerobic endurance competition. It also emphasizes the importance of a high V[Combining Dot Above]O2max for aerobic endurance athletes and may partly explain the V[Combining Dot Above]O2 slow component as impaired RE.

Lifelong strength training mitigates the age-related decline in efferent drive

Recently, we documented age-related attenuation of efferent drive to contracting skeletal muscle. It remains elusive if this indication of reduced muscle strength is present with lifelong strength training. For this purpose, we examined evoked potentials in the calf muscles of 11 [71 ± 4 (SD) yr] strength-trained master athletes (MA) contrasted with 10 (71 ± 4 yr) sedentary (SO) and 11 (73 ± 6 yr) recreationally active (AO) old subjects, as well as 9 (22 ± 2 yr) young controls. As expected, MA had higher leg press maximal strength (MA, 185 ± 32 kg; AO, 128 ± 15 kg; SO, 106 ± 11 kg; young, 147 ± 22 kg, P < 0.01) and rate of force development (MA, 5,588 ± 2,488 N/s; AO, 2,156 ± 1,100 N/s; SO, 2,011 ± 825 N/s; young, 3,663 ± 1,140 N/s, P < 0.05) than the other groups. MA also exhibited higher musculus soleus normalized V waves during maximal voluntary contractions (MVC) [maximal V wave amplitude/maximal M wave during MVC (Vsup/Msup); 0.28 ± 0.15] than AO (0.13 ± 0.06, P < 0.01) and SO (0.11 ± 0.05, P < 0.01), yet lower than young (0.45 ± 0.12, P < 0.01). No differences were apparent between the old groups in H reflex recorded at rest or during MVC [maximal H reflex amplitude/maximal M wave during rest (Hmax/Mmax); maximal H reflex amplitude during MVC/maximal M wave during MVC (Hsup/Msup)], and all were lower (P < 0.01) than young. MA (34.4 ± 2.1 ms) had shorter (P < 0.05) H reflex latency compared with AO (36.4 ± 3.7 ms) and SO (37.3 ± 3.2 ms), but longer (P < 0.01) than young (30.7 ± 2.0 ms). Using interpolated twitch analysis, MA (89 ± 7%) had plantar flexion voluntary activation similar to young (90 ± 6%), and this was higher (P < 0.05), or tended to be higher (P = 0.06-0.09), than SO (83 ± 10%) and AO (84 ± 5%). These observations suggest that lifelong strength training has a protective effect against age-related attenuation of efferent drive. In contrast, no beneficial effect seems to derive from habitual recreational activity, indicating that strength training may be particularly beneficial for counteracting age-related loss of neuromuscular function.

The Effect of Physical Activity on Passive Leg Movement-Induced Vasodilation with Age

INTRODUCTION Because of reduced nitric oxide (NO) bioavailability with age, passive leg movement (PLM)-induced vasodilation is attenuated in older sedentary subjects and, unlike the young subjects, cannot be augmented by posture-induced elevations in femoral perfusion pressure. However, whether vasodilator function assessed with PLM, and therefore NO bioavailability, is preserved in older individuals with greater physical activity and fitness is unknown. METHODS PLM was performed on four subject groups: young sedentary (Y, 23 ± 1 yr, n = 12), old sedentary (OS, 73 ± 2 yr, n = 12), old active (OA, 71 ± 2 yr, n = 10), and old endurance trained (OT, 72 ± 1 yr, n = 10) in the supine and upright-seated posture. Hemodynamics were measured using ultrasound Doppler and finger photoplethysmography. RESULTS In the supine posture, PLM-induced peak change in leg vascular conductance was significantly attenuated in the OS compared with the young subjects (OS = 4.9 ± 0.5, Y = 6.9 ± 0.7 mL·min·mm Hg) but was not different from the young in the OA and OT (OA = 5.9 ± 1.0, OT = 5.4 ± 0.4 mL·min·mm Hg). The upright-seated posture significantly augmented peak change in leg vascular conductance in all but the OS (OS = 4.9 ± 0.5, Y = 11.8 ± 1.3, OA = 7.3 ± 0.8, OT = 8.1 ± 0.8 mL·min·mm Hg), revealing a significant vasodilatory reserve capacity in the other groups (Y = 4.92 ± 1.18, OA = 1.37 ± 0.55, OT = 2.76 ± 0.95 mL·min·mm Hg). CONCLUSIONS As PLM predominantly reflects NO-mediated vasodilation, these findings support the idea that augmenting physical activity and fitness can protect NO bioavailability, attenuating the deleterious effects of advancing age on vascular function.