need reasons why low weight/high rep shizbit is bad

[Gladiola]

Hi Muskles,

I know you will find plenty of reasons why heavy lifting is GOOD, but how about some reasons why light weight-hi reps is BAD (irrelevant of heavy lifting)??

I teach BodyPump classes & I only do it a few times a month (I'm considering dropping it altogether). You really would not believe the OVER USE INJURIES ppl experience from it. I can direct her to an aerobics-instruction bulletin board where debates rage - but there is plenty of talk of sore joints that can easily be attributed to this type of training.

I do agree that a variety of training is best & ideal for hitting all muscle fibers, but ONLY doing BodyPump classes several times a week would certainly lead someone to over use injuries.

 

[sysopt]

the only good thing about that aerobic dancing shit is the nice lookin ladies bouncin around

 

[wilson6]

Lets get this straight.

Muscle fibers are recruited in an orderly fashion depending on the type of contraction desired (recruitment threshold of the motor nerve). Type I motor nerves have the lowest recruitment threshold, thus they are recruited first.

In general, the order of recruitment is Type I first, then Type IIa, then IIx, then IIb depending on the force required. For low to moderate intensity intermittent or continuous movements, Type I fibers are recruited. When the Type I fibers fatigue, Type II are recruited, but fatigue quickly. An explosive contraction will recruit all fibers, but there is some evidence that Type II fibers may have a lower recruitment threshold than Type I fibers during sudden explosive movements. Thus, they may be recruited first, but Type I will still be recruited.

High rep-light weight training will generally only recruit Type I fibers, maybe some Type IIa if the set is taken to fatigue. In general, most of you have VERY FEW Type IIb fibers in your muscles. A high percentage of IIb fibers are generally only observed in very sedentary people. Any sort of activity (weights, aerobics, etc.) will shift IIb to IIa. None-the-less, you still need explosive contractions to recruit the Type II fibers in order to build size because Type II fibers increase in cross-sectional area much more so than Type I fibers. Force production is a function of both frequency of motor unit firing and number of motor units recruited for a particular muscle group. To fully recruit all fibers you need all motor units firing, and at maximal firing frequency.

In resistance training terms, this would mean mixing the type of work you do. This is one of the reasons we do both higher reps and lower explosive reps in the same workout. Legs for example, the lower rep squats come first and are followed by high rep leg presses, but with weight that causes complete fatigue by 50 reps (i.e., 500 – 1000 lbs), not a couple of 25 lbs plates on each side that I see with some of the high rep-light weight crowds. With other body parts, drop sets will facilitate the same effect. Fatigue the Type II fibers first then finish off the Type I fibers with drop sets to failure. Ever start with triceps pressdowns at 150 lbs and find that finishing the last set with 30 lbs is tough, that’s the last of the Type I fibers you are recruiting.

Bottom line. Mix the rep/weight scheme in the workout. Always start with a heavy weight-low (6-10) rep exercise (after proper warm-up) when you have the most energy, then finish with some drop sets. None-the-less, high rep-light weight ONLY is a waste of time. Might as well take a power aerobics class. Although the fitness chicks use that program along with a lot of OX and get the desired results, still would be cheaper just to lift heavier and not use the OX. But that’s fitness.

W6

 

[wilson6]

"There is a workout that is designed in the high rep category to elicit weight loss without compromising muscular strength. It's called Poliquin's German Body Composition Training. It's targeted in the 10-20 rep range. "


10 - 20 reps is not high rep in my book, and yes that rep range can build considerable strength, muscle mass and increase metabolic rate. Now, if you're a powerlifter, then that would be considered high reps, but for most of you on this board, the 10 - 20 rep range would work fine. However, throwing in a day of speed sets on bench or squat (i.e., 10 sets of 2 or 3 reps with 20 - 30 sec rest between sets) works wonders every 6-8 weeks or so even for physique competitors. Even a workout with 4 or 5 sets of 5 RM on a particular core exercise like benches or squats is fine, but don't try that after doing high reps. Stay away from 1 RM lifts, too much room for injury.

Mix it up for continuous gains.

W6

 

[Gladiola]

the only good thing about that aerobic dancing shit is the nice lookin ladies bouncin around

Alright, I couldn't let this one go.

BodyPump is muscular endurance training in a group setting.

"Aerobic Dance" is an entirely different thing.. just happens to also be in a group setting.

The aerobic dance classes I teach incorporate hi-impact moves & are VERY high intensity. It's running, jumping etc. with *style* & to cool music.

All we really need to do to get our Heart Rates up is MOVE (there's nothing inherently unique about running that makes it good cardio, it's putting one foot in front of the other quickly). We aerobic dance participants choose to do cardio in a more fun way.... AND look hot doing it and it's still an awesome cardio workout.

 

[sysopt]

Either way, cardio's effective for building muscle and shedding fat is terrible. I still don't mind watching though .

W6, I've heard some people say that fiber recruitment is directly dependent upon the weight lifted, not the tempo (ie explosiveness). For example, if you lift a light weight with the same force as a much heavier weight, (ie exploding) you won't pull up more than the type IIa's. The benefits of explosive lifting is better fiber recruitment down the line and better neurological coordination. This is why many studies have shown that the group that lifts explosively is stronger.

 

[wilson6]

sysopt

"if you lift a light weight with the same force as a much heavier weight"

Same force? Not sure what you're saying. Force would be greater with a heavier weight. Sure you don't mean velocity of contraction? and if so, you won't need to recruit as many fibers with a lighter weight using the same velocity of contraction. But a fast contraction would require some Type II involvement.

Yes, motor unit recruitment depends on the force needed and more force is required to lift heavy weight, thus greater motor unit recruitment including Type II fibers.

However, you can take a submax weight (something you could get 12 - 15 reps with), let's say 275 on the bench and perform explosive reps (speed sets) of 2 or 3 reps with short rest breaks (20-30 sec) 2-0-0.5 tempo. This type of activity, even though it is submax weight may activate Type II motor units first. Whereas if you moved the same weight with a 4-0-4 tempo, the recruitment pattern would be different, probably recruiting Type I first.

Velocity of the contraction is also important. Type II fibers generate a greater velocity of contraction when recruited.


W6