Re: Contractions duration.

[Guest guest]

I don't know what this proves. I don't know of anyone who has

recommended using 3 second isos at 70% of max.

In fact, I remember Muller had already tested that duration way back

in the 1950s and concluded that 7 seconds was pretty much needed for

any training effect.

A better study would have been 7-10 seconds at Max vs the longer

durations. Then we would have a more valid comparison of longer vs

shorter.

Moreover, I am not sure the left leg vs right leg approach is

correct. One could argue that one leg learns more effectively than

another, ie right handed folks etc.

Interesting though.

The role of metabolites in strength training. II. Short versus long

isometric contractions.

Schott J, McCully K, Rutherford OM.

Department of Physiology, St. 's Hospital Medical School, London,

UK.

The role of intramuscular metabolite changes in the adaptations

following isometric strength training was examined by comparing the

effect of short, intermittent contractions (IC) and longer,

continuous (CC) contractions. In a parallel study, the changes in

phosphate metabolites and pH were examined during the two protocols

using whole-body nuclear magnetic resonance spectroscopy (NMRS).

Seven subjects trained three time per week for 14 weeks. The right

leg was trained using four sets of ten contractions, each lasting 3 s

with a 2-s rest period between each contraction and 2 min between

each set.

The left leg was trained using four 30-s contractions with a 1-min

rest period between each. Both protocols involved isometric

contractions at 70% of a maximum voluntary isometric contraction

(MVC). The MVC, length:tension and force:velocity relationships and

cross-sectional area (CSA) of each leg were measured before and after

training. The increase in isometric strength was significantly

greater (P = 0.041) for the CC leg (median 54.7%; P = 0.022) than for

IC (31.5%; P = 0.022). There were no significant differences between

the two protocols for changes in the length:tension or force:velocity

relationships. There were significant increases in muscle CSA for the

CC leg only. NMRS demonstrated that the changes in phosphate

metabolites and pH were greater for the CC protocol. These findings

suggest that factors related to the greater metabolite changes during

CC training results in greater increases in isometric strength and

muscle CSA.

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> 7. Schott, J., McCully, K., & Rutherford, O.M.

(1995). The role of metabolites in strength training

II: Short versus long isometric contractions.

European Journal of Applied Physiology, 71, 337–341

>

> In a related study, long fatiguing isometric muscle actions

(four isometric muscle actions lasting 30 seconds

each) were compared to shorter and less fatiguing

isometric muscle action (four sets of 10 contractions,

each lasting three seconds) [7].

> Although the muscle was under tension for the same

amount of time (120 seconds), gains in muscle strength

were greater with the longer isometric muscle actions,

which caused a greater amount of muscle fatigue.

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