Effect of Manipulating Intensity Flashcards
Intensity - Definition
The % of a 1-repetition maximum (RM) lift
The absolute load for a 3-RM, 5RM, 10RM, 15-RM etc prescription
But isn’t manipulating rest-interval with a moderate load ‘intense’
- Effort (voluntary activation) vs Intensity
The Conundrum
- The observational history of our field dictated the belief that higher intensities must be more effective for strength, and lower intensities (10-15RM range) must be more effective for hypertrophy (owing to anabolic hormone hypothesis)
- The last decade of research however, has provided evidence questioning the magnitude of impact these intensity zones have on training goals.
- The pendulum in some instances however, may have swung too far back the other way.
Untrained populations/ Novice
STUDY: High Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High Load Low Volume Resistance Exercise in Young Men
- Method/groups (90%FAIL, 30%Work, 30% FAIL)
- Results
- Conclusion HINT: at the same volume…
Method
- Leg extension
- Crossover design
- 4 sets of either
* 90% FAIL
* 30% Work Matched to 90% session
* 30% FAIL (continue multiple sets until complete exhaustion)
- Standardized feeding around all protocols
Results
- After 4 hrs, the 30Fail group experienced a larger amount of synthesis of p70S6K THr389, which then reduced after 24 hrs
- After 4hrs, the 30Fail group experienced a larger amount of 4E-BP1, however, the amount increased after 24hrs for all groups
- After 4hrs, the 90Fail and 30Fail experienced the highest amount of myofibrillar FSR, however, the 30Fail group had the highest amount of myofibrillar FSR after 24hrs
Conclusion
- At the same ‘volume’ intensity was better for upregulating intrinsic mechanisms linked to muscle hypertrophy
- When higher volume was accrued, intensity did not matter
- You would need to have a higher volume with low intensity exercise to achieve similar results as having a lower volume with high intensity exercise (despite the myofibrillar FSB being reduced after 24 hrs for the 90Fail group)
- The Results suggest that low load high volume resistance exercise is more effective in inducing acute muscle anabolism than high load low volume or work matched resistance exercise mode
Untrained populations/ Novice
STUDY: Age-related difference in the dose-response relationship of muscle protein synthesis to resistance exercise in young and old men
This study controlled for volume at different intensities. This article supports higher intensities as for both the young and older individuals experienced a higher FSR at higher intensities
- So at matched volumes across a range of intensities “intensity” is important for upregulating hypertrophic mechanisms (KUMAR), but if you allow for volume to become higher intensity not as important (BURD)
- The rationale for volume accrual at any intensity is thought that as you get closer to repetition failure (RM) you will eventually achieve full recruitment of the motor unit pull.
- Caveat: Hard to confirm hypothesis due to limitations of surface EMG as a primary measure of “recruitment”. However, assessment of a combination of indirect measures does give support to this conjecture/theory.
Untrained populations/ Novice
STUDY: The Magnitude of Peripheral Muscle Fatigue Induced by High and Low Intensity Single Joint Exercise Does Not Lead to Central Motor Output Reductions in Resistance Trained Men
HINT:
- The 80% group saw…
- The 40% group saw…
- if intensities are low…
- The 80% group saw a 90% voluntary activation in the first five sec which then started to decrease. During the final stage (11sec), there was an increase in voluntary contraction
- The 40% group saw a 65% voluntary contraction in the first five sec which was maintained for 30 sec. During the final stage (46sec), there was an increase in voluntary activation to a % that was similar to the 90% group
If intensities are low enough but you do it at a high enough volume to a repetition maximum eventually you can get similar motor unit recruitment levels as you would see in high intensity groups. However, it the efficiency or the amount of time it takes you to get there is a lot longer
Untrained Population/ Novices
HINT: Low intensity exercise elicits…
Motor unit recruitment…
- Low intensity exercise elicits greater peripheral muscle fatigue, probably owning to the total time under tension to achieve similar overall volume
- Motor unit recruitment is generally different between high and low intensity contractions, apart from where we increase volume and require a low intensity contraction to be performed to failure.
- In this case, low intensity contractions appear to achieve similar levels of central motor output to a high intensity contraction, but only towards the end of the contraction.
- When you increase ‘volume’ of repetitions by 4-5x that of a higher intensity load (i.e. 20 reps at 80-90% vs 90-100 reps at 40%) you will likely achieve similar central motor output and upregulation of muscle protein synthesis
Untrained Population/ Novice
STUDY: Muscular Adaptations in response to three different resistance-training regimes: specificity of repetition maximum training zones
- low, intermediate, high rep groups
Low (3-5), intermediate (9-11), high (20-28) rep
- Data showed that the most amount of strength gain occurred in the low rep group while that the largest gain in endurance was from the high rep condition
- Both the low and intermediate group saw increases in both muscle fibre type (type 1 & Type 2A/2B), however, none of the differences between the high rep group were deemed statistically significant.
Gives evidence for the Kumar paper
- Shows that there was no correlation between the amount of P70S6K and changing quadriceps volume
Untrained Population/ Novice
STUDY:Resistance exercise load does not determine training mediated hypertrophic gains in young men.
80% 1RM - 1 set to failure
80% 1RM - 3 sets to failure
30% 1RM - 3 sets to Failure
80% 1RM - 1 set to failure
80% 1RM - 3 sets to failure
30% 1RM - 3 sets to Failure
- Results not statistically significant . Evidence leaning towards the higher volume groups (30% 3 sets). The 80% 3 sets showed a greater trend in quadricep volume change (increases in hypertrophy) compared to the lower 80% 1 set
- Similar hypertrophic outcomes between groups
- Low intensity failure training has a localized strength effect in the part of the range of motion where the primary effort is delivered, but for maximal strength development throughout the range of motion heavier loading is needed
- Specificity of adaptation is a load-movement dependent effect
Untrained Populations/ Novice
STUDY: Greater Neural Adaptations following High vs Low-Load Resistance Training
- voluntary recruitment/activation
HINT: the higher intensity group experienced…
The higher intensity group experienced strength gains earlier than the low intensity group
For the 30RM group, not enough fatigue was acquired to actually see changes in voluntary recruitment. So we’ve seen an increase in voluntary activation to your ability to recruit motor units in the higher intensity group. This can be because the low intensity group probably didn’t do enough volume to account for the differences here
Untrained Populations/ Novice
It doesn’t matter what intensity you use to initiate training gains
- Emphasis on strength: use higher intensity (Dynamic strength?)
- Emphasis on hypertrophy, accumulate volume
- If use ‘heaver’ weight (e.g. 80%+) you can use less volume
- If use “lighter” weight you must prescribe multiple sets to failure
Accumulation of ‘volume’ probably more important for novices to enhance outcomes.
Trained Populations
- No difference in hypertrophic outcomes between 10-25RM type loading
- Must ensure for lighter loading that volume is maximized
- Likely that if volume is equated, higher intensity loading will be beneficial (i.e. boost volume in the 12-15RM range for more time efficient workout and volume accumulation for hypertrophic goals)
- Strength outcomes tend to become more pronounced in compound movements with higher intensity
- Relative loading of the different muscles vs absolute load of the exercise (isolation vs compound)
- Differences in strength and hypertrophy appear to become pronounced between 10-12RM loading and 4-6RM type loading, regardless of volume differences (but if you start undulating from day-to-day so there is overlap, you will negate likely differences
- Must be careful of volume accumulation near the 4RM intensity banding (more on this shortly)
