Hemodynamic and left ventricular systolic function were studied by Doppler echocardiography in 14 young and 15 older adult hypertensive patients and in 15 young and 12 older normotensive individuals. Measures were made at rest and during upright deadlift isometric exercise, at 30% of maximum voluntary contraction for 3 min. At rest, young and older hypertensive patients demonstrated impaired left ventricular systolic function compared to both old and young normotensive subjects. The impaired systolic function was associated with less augmentation in systolic indices during exercise compared with resting values in young and elderly hypertensive patients, and to a lesser degree in the normotensive elderly when compared with young normotensives. These data indicate that at rest, left ventricular systolic function may be compromised in hypertensive patients with left ventricular hypertrophy and, to a lesser extent, in the normotensive elderly. However, other factors in chronic hypertension may contribute to abnormal systolic function and override the effects of aging alone.
Michael Sagiv, Amira Sagiv, David Ben-Sira, Jacob Rudoy and Michael Soudry
Deanna L. Huggett, Ian D. Elliott, Tom J. Overend and Anthony A. Vandervoort.
The authors compared heart-rate and blood-pressure responses to typical isometric (ISO) and isokinetic (90°/s) eccentric (ECC) resistance-training protocols in older adults. Twenty healthy older adults (74 ± 5 years old) performed randomly ordered ISO and isokinetic ECC exercise (3 sets of 10 repetitions) at a target intensity of 100% of their peak ISO torque value. Heart rate and systolic (SBP) and diastolic (DBP) blood pressures were recorded continuously, and mean arterial pressure (MAP) and rate-pressure product (RPP) were calculated. ECC peak torque (139 ± 33 N · m) was significantly greater than ISO peak torque (115 ± 26 N · m; p < .001). All variables increased significantly (p < .001) during both ISO and ECC exercise. Changes in SBP, DBP, MAP, and RPP were significantly greater during ISO exercise than during ECC exercise (p < .001). Clinically, an isokinetic ECC exercise program enables older adults to work at the same torque output with less cardiovascular stress than ISO exercise.
Eric R. Helms, Caryn Zinn, David S. Rowlands, Ruth Naidoo and John Cronin
Athletes risk performance and muscle loss when dieting. Strategies to prevent losses are unclear. This study examined the effects of two diets on anthropometrics, strength, and stress in athletes.
This double-blind crossover pilot study began with 14 resistance-trained males (20-43 yr) and incurred one dropout. Participants followed carbohydrate-matched, high-protein low-fat (HPLF) or moderate-protein moderate-fat (MPMF) diets of 60% habitual calories for 2 weeks. Protein intakes were 2.8g/kg and 1.6g/kg and mean fat intakes were 15.4% and 36.5% of calories, respectively. Isometric midthigh pull (IMTP) and anthropometrics were measured at baseline and completion. The Daily Analysis of Life Demands of Athletes (DALdA) and Profile of Mood States (POMS) were completed daily. Outcomes were presented statistically as probability of clinical benefit, triviality, or harm with effect sizes (ES) and qualitative assessments.
Differences of effect between diets on IMTP and anthropometrics were likely or almost certainly trivial, respectively. Worse than normal scores on DALDA part A, part B and the part A “diet” item were likely more harmful (ES 0.32, 0.4 and 0.65, respectively) during MPMF than HPLF. The POMS fatigue score was likely more harmful (ES 0.37) and the POMS total mood disturbance score (TMDS) was possibly more harmful (ES 0.29) during MPMF than HPLF.
For the 2 weeks observed, strength and anthropometric differences were minimal while stress, fatigue, and diet-dissatisfaction were higher during MPMF. A HPLF diet during short-term weight loss may be more effective at mitigating mood disturbance, fatigue, diet dissatisfaction, and stress than a MPMF diet.
Dae-Hyun Kim, Jin-Hee Lee, Seul-Min Yu and Chang-Man An
can be an alternative method. Isometric contraction involves muscular actions in which the length of the muscle does not change and no movement of the joint is visible. 10 Isometric exercise can be used for general strength conditioning and for rehabilitation, when strengthening the muscles without
Kenneth R. Turley, D. Eric Martin, Eric D. Marvin and Kelley S. Cowley
To determine the reliability of cardiovascular responses to isometric exercise of different intensities, and to compare adult versus child responses, 27 boys (7–9 years old) and 27 men (18–26 years old) performed static handgrip exercise at 10, 20, and 30% of previously determined maximal voluntary contraction (MVC) for three min each on different days, while heart rate (HR) and blood pressure (BP) were measured. HR reliability was moderately high at all intensities in both boys and men ranging from R = 0.52–0.87. BP reliability was moderate in men and boys at 30% MVC while at 10% and 20% MVC reliability was very low for boys and only moderate for men. HR response from pre- to 3-min of static exercise was not different between boys versus men at any intensity. At 30% MVC diastolic (20.2 vs. 29.3 mmHg), systolic (17.4 vs. 36.2 mmHg) and mean (19.2 vs. 31.6 mmHg) BP responses were lower in boys versus men, respectively. At 20% MVC SBP (6.8 vs. 14.3 mmHg) and MBP (8.4 vs. 12.6 mmHg) responses were lower in boys versus men, respectively. In conclusion, the reliability of cardiovascular response to isometric exercise is low at low contraction intensities and moderate at higher contraction intensities. Further, BP response in men at 30% MVC is higher than boys, while responses are similar at lower contraction intensities.
Richard L. Urbanski, Steven F. Loy, William J. Vincent and Ben B. Yaspelkis III
Ten physically active, untrained, college-aged males (26.4 ± 5.8 years old) received creatine (CR. 5 g creatine monohydrate + 3 g dextrose) and placebo (PLA, 7 g dextrose) supplementation four times per day for 5 days in a double-blind, randomized, balanced, crossover design. Performance was assessed during maximal and three repeated submaximal bouts of isometric knee extension and handgrip exercise. CR supplementation significantly increased (p < .05) maximal isometric strength during knee extension but not during handgrip exercise. CR supplementation increased time to fatigue during each of the three bouts of submaximal knee extension and handgrip exercise when compared to the PLA trials. These findings suggest that CR supplementation can increase maximal strength and lime to fatigue during isometric exercise. However, the improvements in maximal isometric strength following CR supplementation appear to be restricted to movements performed with a large muscle mass.
Alexandre G. da Silva, Mauricio M. Ribeiro, Ivani C. Trombetta, Christiane Nicolau, Eliana Frazzatto, Isabel Guazzelli, Luciana N. J. Matos, Alfredo Halpern, Carlos E. Negrão and Sandra M.F. Villares
This study examined forearm vasodilatation during mental challenge and exercise in 72 obese children (OC; age = 10 ± 0.1 years) homozygous with polymorphism in the allele 27 of the β2-adrenoceptors: Gln27 (n = 61) and Glu27 (n = 11). Forearm blood flow was recorded during 3 min of each using the Stroop color-word test (MS) and handgrip isometric exercise. Baseline hemodynamic and vascular measurements were similar. During the MS, peak forearm vascular conductance was significantly greater in group Glu27 (Δ = 0.35 ± 0.4 vs. 0.12 ± 0.1 units, respectively, p = .042). Similar results were found during exercise (Δ = 0.64 ± 0.1 vs. 0.13 ± 0.1 units, respectively, p = .035). Glu27 OC increased muscle vasodilatory responsiveness upon the MS and exercise.
Ben M. Krings, Brandon D. Shepherd, Hunter S. Waldman, Matthew J. McAllister and JohnEric W. Smith
al., 2017 ), RE session volume ( Bastos-Silva et al., 2019 ; Decimoni et al., 2018 ), isokinetic exercise ( Bailey et al., 2019 ; Bazzucchi et al., 2016 ), and isometric exercise ( Jensen et al., 2015 ). However, CMR has also been found to not improve maximal muscular strength, endurance ( Clarke et
David Giles, Joel B. Chidley, Nicola Taylor, Ollie Torr, Josh Hadley, Tom Randall and Simon Fryer
fatigue due to incremental isometric exercise . J Appl Physiol . 2002 ; 93 ( 5 ): 1813 – 1823 . PubMed ID: 12381770 doi:10.1152/japplphysiol.00091.2002 10.1152/japplphysiol.00091.2002 12381770 23. Simpson LP , Jones AM , Vanhatalo A , Wilkerson DP . Influence of initial metabolic rate on the
Fábio J. Lanferdini, Rodrigo R. Bini, Bruno M. Baroni, Kelli D. Klein, Felipe P. Carpes and Marco A. Vaz
pioneers to show enhanced exercise performance in humans through LLLT, further supported by studies assessing muscle fatigue and exercise recovery with LLLT and/or LEDT before performing isoinertial exercise, 12 – 16 isometric exercise, 17 – 19 isokinetic exercise, 20 , 21 cycling exercise, 22 – 25 and