вторник, 4 марта 2014 г.

High-intensity interval resistance training boosts EPOC

Strength athletes burn more calories than normal for days after a training session thanks to the EPOC effect. Italian researchers at the University of Padova have discovered that a training method they call high-intensity interval resistance training boosts post-workout calorie burning even more than traditional strength training.

Strength athletes burn more calories than normal for days after a training session thanks to the EPOC effect. Italian researchers at the University of Padova have discovered that a training method they call high-intensity interval resistance training boosts post-workout calorie burning even more than traditional strength training.
EPOC is short for excess post-exercise oxygen consumption. In the 20th century physiologists discovered that after a high-intensity cardio training session or a strength-training workout the level of oxygen burned by the body remains elevated, and that the body is thus burning extra calories. After intensive exertion the body needs to repair all sorts of things and recover, both of which cost extra energy.
The EPOC effect is also referred to as the after-burn effect.
Brandt got 16 untrained women to do abductions on a machine [below left] and with an elastic band [below right]. The women used TheraBand exercise bands. Brandt placed electrodes on the women’s legs, glutes and core muscles so he could measure the electrical activity in their muscles, which gave an indication of how intensively the women were using their muscles.
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Interval training raises EPOC, as does strength training, so the researchers surmised that a combination of these two types of training might result in an extra strong EPOC effect. They published a study in the Journal of Translational Medicine in 2012 in which they described how they had tested this theory in an experiment involving 17 well-trained male strength athletes.
The researchers got their subjects to do strength training on two occasions, and measured how many calories the men burned in the first 22 hours after each session.
On one occasion the men trained in a traditional manner: they performed eight exercises, covering the largest muscle groups. They did 4 sets of each exercise using a weight with which they could manage a maximum of 12 reps. Between sets they rested for 1-2 minutes.
On the other occasion the men did high-intensity interval resistance training: they trained using weights with which they could just manage 6 reps. First they performed 1 set at failure, rested 20 seconds and then performed another set at failure. Most only managed 2 reps in the second set. The subjects then rested for another 20 seconds and then performed another set at failure.
For each of the upper-body exercises the men did two of these series. For the leg-muscle exercises they did three.
The men did just 3 exercises: the leg-press, chest-press and lat-row.
The figure below shows that the traditional form of strength training raised the men’s calorie burning by 98 calories in the 22 hours after the workout. The high-intensity interval resistance training boosted the men’s calorie burning by a whopping 452 calories.
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The men’s respiratory ratio [RR] was reduced after the high-intensity interval training, which would indicate that their fat burning increased.
Including the warming up the high-intensity interval training lasted 32 minutes. The Italians conclude that the short time required and the strong effect on fat burning opens up interesting perspectives.
“Our results suggest that high-intensity interval resistance training increases excess post exercise energy consumption to a significantly greater extent than traditional resistance training”, the researchers write. “This exercise methodology allows subjects to improve metabolism and, at the same time, muscle mass and strength all of which are promoted as beneficial by many guidelines. In Western society leisure time is lacking and motivation to perform daily exercise is uncommon resulting in low overall levels of daily lifestyle related physical activity.”

High-Intensity Interval Resistance Training (HIRT) influences resting energy expenditure and respiratory ratio in non-dieting individuals.

Paoli A1, Moro T, Marcolin G, Neri M, Bianco A, Palma A, Grimaldi K.
Abstract
BACKGROUND:
The benefits of exercise are well established but one major barrier for many is time. It has been proposed that short period resistance training (RT) could play a role in weight control by increasing resting energy expenditure (REE) but the effects of different kinds of RT has not been widely reported.
METHODS:
We tested the acute effects of high-intensity interval resistance training (HIRT) vs. traditional resistance training (TT) on REE and respiratory ratio (RR) at 22?hours post-exercise. In two separate sessions, seventeen trained males carried out HIRT and TT protocols. The HIRT technique consists of: 6 repetitions, 20?seconds rest, 2/3 repetitions, 20 secs rest, 2/3 repetitions with 2’30? rest between sets, three exercises for a total of 7 sets. TT consisted of eight exercises of 4 sets of 8-12 repetitions with one/two minutes rest with a total amount of 32 sets. We measured basal REE and RR (TT0 and HIRT0) and 22?hours after the training session (TT22 and HIRT22).
RESULTS:
HIRT showed a greater significant increase (p?< ?0.001) in REE at 22?hours compared to TT (HIRT22 2362?±?118 Kcal/d vs TT22 1999?±?88 Kcal/d). RR at HIRT22 was significantly lower (0.798?±?0.010) compared to both HIRT0 (0.827?±?0.006) and TT22 (0.822?±?0.008).
CONCLUSIONS:
Our data suggest that shorter HIRT sessions may increase REE after exercise to a greater extent than TT and may reduce RR hence improving fat oxidation. The shorter exercise time commitment may help to reduce one major barrier to exercise.
PMID: 23176325 [PubMed - indexed for MEDLINE] PMCID: PMC3551736

Stretch and anabolic steroid combination produces muscle growth

Imagine: an injury means you can’t train for a while, but you can use anabolic steroids. In this hypothetical situation you can maintain more muscle mass by doing stretch exercises. You may even be able to build up a little bit of muscle mass, according to an animal study that sports scientists published in Scientific World Journal.

The researchers, who work at Kagoshima University in Japan, gave rats methenolone [an anabolic steroid, structural formula shown above] in a dose of 20 mg/kg bodyweight. The human equivalent of this dose is about 200-300 mg. The researchers injected the steroid directly into the small intestine.
A control group was given no methenolone.
The rats were sedated, which meant that the researchers could stretch the animals’ right-hand gastrocnemius muscle. They did this 15 times a minute for 15 consecutive minutes. The researchers did nothing with the left-hand gastrocnemius.
Imagine: an injury means you can’t train for a while, but you can use anabolic steroids. In this hypothetical situation you can maintain more muscle mass by doing stretch exercises. You may even be able to build up a little bit of muscle mass, according to an animal study that sports scientists published in Scientific World Journal.
Twenty-four hours later the Japanese observed that the combination of stretches and the anabolic steroid had boosted the synthesis of Mechano Growth Factor [MGF]. Mechano Growth Factor is a stripped down version of IGF-1 [structural formula shown above]. Fundamental research has shown that the anabolic effect of MGF is so strong that the researchers are convinced that the combination brings about muscle growth.
White bars: cells from muscles that were not stretched; black bars: cells from muscles that were stretched.
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The researchers also looked at the synthesis of the anabolic signal proteins Myo-D and myogenin, but found no effect.
“Mechanical stimulation of skeletal muscle in conjunction with the administration of an anabolic steroid induced mRNA expression of MGF”, the researchers conclude. “This finding suggests that the combination of anabolic steroids with muscle stretching exercise could promote muscle strengthening in patients with muscle weakness.”
The reason that the researchers don’t attach so much importance to the absence of an effect of the stretch-methenolone combination on Myo-D and myogenin is probably to be found in an animal study they published earlier, in May 2013. [ScientificWorldJournal. 2013 May 23;2013:493656.]
In that study the researchers used no steroids. In one group of experimental animals the researchers kept the right gastrocnemius muscle stretched for 15 minutes [SSC] and did nothing with the left gastrocnemius [USC].
In another group of rats the researchers stretched the right gastrocnemius 15 times a minute for a period of 15 minutes [SSR], and did nothing with the left gastrocnemius [USR]. This is also the protocol that the researchers used in the experiments when they gave the rats methenolone.
At the end of the week the researchers observed an increased synthesis of Myo-D [first figure below] and myogenin [second figure] in the SSR group. Apparently muscle cells subjected to stretching need longer than a day to boost the production of Myo-D and myogenin.
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“In conclusion, passive stretching for a short duration once daily at several days within a 1-week period is effective in the growth of the skeletal muscle”, the researchers conclude in the older study. “Repetitive stretching is suggested to have greater effects than continuous stretching. These findings suggest that passive stretching is useful in the prevention and maintenance of skeletal muscle tone in patients who are unconscious or paralyzed.”

The effect of anabolic steroid administration on passive stretching-induced expression of mechano-growth factor in skeletal muscle.

Abstract
BACKGROUND:
Stretching of skeletal muscle induces expression of the genes which encode myogenic transcription factors or muscle contractile proteins and results in muscle growth. Anabolic steroids are reported to strengthen muscles. We have previously studied the effects of muscle stretching on gene expression. Here, we studied the effect of a combination of passive stretching and the administration of an anabolic steroid on mRNA expression of a muscle growth factor, insulin-like growth factor-I autocrine variant, or mechano-growth factor (MGF).
METHODS:
Twelve 8-week-old male Wistar rats were used. Metenolone was administered and passive repetitive dorsiflexion and plantar flexion of the ankle joint performed under deep anesthesia. After 24 h, the gastrocnemius muscles were removed and the mRNA expression of insulin-like growth factor-I autocrine variant was measured using quantitative real-time polymerase chain reaction.
RESULTS:
Repetitive stretching in combination with metenolone, but not stretching alone, significantly increased MGF mRNA expression.
CONCLUSION:
Anabolic steroids enhance the effect of passive stretching on MGF expression in skeletal muscle.
PMID: 24062630 [PubMed - in process] PMCID: PMC3767052