Growth hormone responses to acute resistance exercise with vascular restriction in young and old men

Abstract

Objective Resistance exercise (RE) stimulates growth hormone (GH) secretion in a load-dependent manner, with heavier loads producing larger GH responses. However, new research demonstrates that low-load RE performed with blood flow restriction (BFR) produces potent GH responses that are similar to or exceed those produced following high-load RE. We hypothesized that low-load RE with vascular restriction would attenuate the known age-related reduction in GH response to RE. Design In a randomized crossover design, ten young (28±7.8 years) and ten older (67.4±4.6 years) men performed bilateral knee extension RE with low-load [20% of one-repetition maximum (1RM)] with BFR and high-load (80% 1RM) without BFR. GH and lactate were measured every 10 minutes throughout a 150-minute testing session (30 minutes prior to and 120 minutes following completion of the exercise); IGF-I was measured at baseline and 60 minutes post-exercise. Results Area under the GH curve indicated that both age groups responded similarly to each exercise condition. However, young men had a significantly greater maximal GH response to low-load RE with BFR than the high-load condition without BFR. Additionally, younger men had greater maximal GH concentrations to low-load RE with BFR than older men (p=0.02). The GH responses were marginally correlated to lactate concentration (r=0.13, p=0.002) and IGF-I levels were unchanged with RE. Conclusions GH responses to low-load RE with vascular restriction are slightly higher than high-load RE without vascular restriction in young men. However, low-load RE with vascular restriction did not attenuate the known age-related reduction in GH response with exercise. These data suggest that while low-load RE with vascular restriction is as effective for inducing a GH response than traditionally-based high-load RE, there is a more potent response in young men.

Neuromuscular Function after a Bout of Low-Load Blood Flow–Restricted Exercise

“…The cuff remained inflated for the duration of the exercise, including the rest periods. A restriction pressure of about 1.3-1.5 times systolic pressure is commonly used in blood flow-restricted resistance exercise studies (7,22,23,35,38).…”

Short Term Technology-Assisted-Aerobic Exercise (AlterGR, GlideTrakTM, Vasper) in a Community Fitness Center for Patients with Mild to Moderate Parkinson’s Disease: Subjective Perceptions and Motor Effects

“…The Nu-Step TM is connected to a vasper (http://vasper.com/) cooling and compression unit [38,50,51]. This system cools both feet, the torso, the upper arms and the thighs (quadriceps and hamstrings) with an option for head cooling.…”

“…Recumbent reciprocal, elliptical cross trainers and recumbent bicycles can also protect against falling and minimize weight bearing loads. More recently, in sports, cooling and compression appear to extend cardiopulmonary benefits, reduce muscle soreness, but increase strength and speed of movement through the release of human growth factors [38,39]. The vasper cooling system (www.vasper.com) provides this option.…”

Time Course Change in Muscle Swelling: High-Intensity vs. Blood Flow Restriction Exercise

“…All of the physiological mechanisms involved in the positive adaptations associated with BFR training are not completely understood, but it has been speculated that acute and chronic increases in hormone secretions [28,34], increased motor unit recruitment, especially Type II fibers increased muscle activation [47], muscle swelling [49], inhibition of myostatin gene expression [22], and activation of anabolic molecular pathways [11,31] play an important role. From the large number of potential proposed mechanisms, muscle swelling has recently received a significant amount of at-tention.…”