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(overfiftylifter @ Jun. 15 2009,9:54)</div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">Does this relate?
APPLIED SCIENCES
Medicine & Science in Sports & Exercise. 26(9):1160-1164, September 1994.
RODNEY, KIERAN J.; HERBERT, ROBERT D.; BALNAVE, RONALD J.
Abstract:
To investigate the role of fatigue in strength training, strength increases produced by a training protocol in which subjects rested between contractions were compared with those produced when subjects did not rest. Forty-two healthy subjects were randomly allocated to either a no-rest group, a rest group, or a control group. Subjects in the two training groups trained their elbow flexor muscles by lifting a 6RM weight 6-10 times on 3 d each week for 6 wk. Subjects in the no-rest group performed repeated lifts without resting, whereas subjects in the rest group rested for 30 s between lifts. Both training groups performed the same number of lifts at the same relative intensity. The control group did not train. Subjects who trained without rests experienced significantly greater mean increases in dynamic strength (56.3% +/- 6.8% (SD)) than subjects who trained with rests (41.2% +/- 6.6%), and both training groups experienced significantly greater mean increases in dynamic strength than the control group (19.7% +/- 6.6%). It was concluded that greater short-term strength increases are achieved when subjects are required to lift training weights without resting. These findings suggest that processes associated with fatigue contribute to the strength training stimulus.
©1994The American College of Sports Medicine</div>
It looked at strength only, which isn't a bad thing per se but..........
Folland also researched this and found the opposite
Br J Sports Med. 2002 Oct;36(5):370-3; discussion 374.
Fatigue is not a necessary stimulus for strength gains during resistance training.
Folland JP, Irish CS, Roberts JC, Tarr JE, Jones DA.
Chelsea School Research Centre, University of Brighton, Eastbourne, UK.
j.folland@bton.ac.uk
BACKGROUND: High resistance training enhances muscular strength, and recent work has suggested an important role for metabolite accumulation in this process. OBJECTIVE: To investigate the role of fatigue and metabolite accumulation in strength gains by comparing highly fatiguing and non-fatiguing isotonic training protocols. METHODS: Twenty three healthy adults (18-29 years of age; eight women) were assigned to either a high fatigue protocol (HF: four sets of 10 repetitions with 30 seconds rest between sets) to maximise metabolic stress or a low fatigue protocol (LF:
40 repetitions with 30 seconds between each repetition) to minimise changes. Subjects lifted on average 73% of their 1 repetition maximum through the full range of knee extension with both legs, three times a week. Quadriceps isometric strength of each leg was measured at a knee joint angle of 1.57 rad (90 degrees ), and a Cybex 340 isokinetic dynamometer was used to measure the angle-torque and torque-velocity relations of the non-dominant leg. RESULTS: At the mid-point of the training, the HF group had 50% greater gains in isometric strength, although this was not significant (4.5 weeks: HF, 13.3 (4.4)%; LF, 8.9 (3.6)%). This rate of increase was not sustained by the HF group, and
after nine weeks of training all the strength measurements showed similar improvements for both groups (isometric strength: HF, 18.2 (3.9)%; LF, 14.5 (4.0)%). The strength gains were limited to the longer muscle lengths despite training over the full range of movement. CONCLUSIONS: Fatigue and metabolite accumulation do not appear to be critical stimuli for strength gain, and resistance training can be effective without the severe discomfort and acute physical effort associated with fatiguing contractions.
The ones that are often cited are
Eur J Appl Physiol Occup Physiol. 1995;71(4):332-6.
The role of metabolites in strength training. I. A comparison of eccentric and concentric contractions.
Smith RC, Rutherford OM.
Department of Physiology, St. Mary's Hospital Medical School, London, UK.
This study examined the role of high forces versus metabolic cost in the adaptations following strength training. Ten young, healthy male and female subjects trained one leg using concentric (CL) and the other using eccentric (EL) contractions of the quadriceps muscle for 20 weeks. EL used weights which were 35% higher than those used for CL. Isometric strength, and the length:tension and force:velocity relationship of the muscle were measured before and after training. Muscle cross-sectional area (CSA) was measured near the knee and hip using computed tomography. Increases in isometric strength were greater for CL compared to EL, the difference being significant with the knee at 1.57 rad (90 degrees) [mean (SD), 43.7 (19.6)% vs 22.9 (9.8)%, respectively; P = 0.01]. Increases in isokinetic strength tended to be larger for EL, although the differences were not significant. Significant increases in CSA occurred near the hip for both EL and CL. These results suggest that metabolic cost, and not high forces alone, are involved in the stimuli for muscle hypertrophy and strength gains following high-resistance training.
and the companion study
Eur J Appl Physiol Occup Physiol. 1995;71(4):337-41.
The role of metabolites in strength training. II. Short versus long isometric contractions.
Schott J, McCully K, Rutherford OM.
Department of Physiology, St. Mary'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.
and
Med Sci Sports Exerc. 2005 Jun;37(6):955-63. Links
The impact of metabolic stress on hormonal responses and muscular adaptations.Goto K, Ishii N, Kizuka T, Takamatsu K.
Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
PURPOSE: The purpose of this study was to examine the impact of exercise-induced metabolic stress on hormonal responses and chronic muscular adaptations. METHODS: We compared the acute and long-term effects of an "NR regimen" (no-rest regimen) and those of a "WR regimen" (regimen with rest period within a set). Twenty-six male subjects were assigned to either the NR (N = 9), WR (N = 9), or control (CON, N = 8) groups.
The NR regimen consisted of 3-5 sets of 10 repetitions at 10-repetition maximum (RM) with an interset rest period of 1 min (lat pulldown, shoulder press, and bilateral knee extension). In the
WR regimen, subjects completed the same protocol as the NR regimen, but took a 30-s rest period at the midpoint of each set of exercises in order to reduce exercise-induced metabolic stress. Acute hormonal responses to both regimens were measured followed by a 12-wk period of resistance training. RESULTS:
Measurements of blood lactate and serum hormone concentrations after the NR and WR regimens showed that the NR regimen induced strong lactate, growth hormone (GH), epinephrine (E), and norepinephrine (NE) responses, whereas the WR regimen did not. Both regimens failed to cause significant changes in testosterone. After 12 wk of resistance training, the NR regimen caused greater increases in 1RM (P < 0.01), maximal isometric strength (P < 0.05), and muscular endurance (P < 0.05) with knee extension than the WR regimen. The NR group showed a marked increase (P < 0.01) in muscle cross-sectional area, whereas the WR and CON groups did not. CONCLUSION: These results suggest that exercise-induced metabolic stress is associated with acute GH, E, and NE responses and chronic muscular adaptations following resistance training.
Taking those three studies can lead one to believe that the acute metabolic stress induced is causitive but when comparing the protocols used it seems clear to me that the differences aren't the metabolic accumulation but the time to peak recruitment and the total time under peak recruitment. This is something that Lawton found out in his study looking specifically at intra-set rest.
J Strength Cond Res. 2006 Feb;20(1):172-6.
Effect of interrepetition rest intervals on weight training repetition power output.
Lawton TW, Cronin JB, Lindsell RP.
Strength and Conditioning, Australian Institute of Sport, Belconnen ACT.
The purpose of this study was to determine the change in weight training repetition power output as a consequence of interrepetition rest intervals. Twenty-six elite junior male basketball and soccer players performed bench presses using a 6 repetition maximum (6RM) load. The power output for each repetition was recorded using a linear encoder sampling each 10 ms (100 Hz). Subjects were assigned to 1 of 3 intervention groups, differentiated by the arrangement of rest intervals within the 6 repetitions: 6 x 1 repetition with 20-second rest periods between each repetition (Singles); 3 x 2 repetitions with 50 seconds between each pair of repetitions (Doubles); or 2 x 3 repetitions with 100 seconds of rest between each 3 repetitions (Triples). A timer was used to ensure that the rest interval and duration to complete all interrepetition interventions was equated across groups (118 seconds). Significantly (p < 0.05) greater repetition power outputs (25-49%) were observed in the later repetitions (4-6) of the Singles, Doubles, and Triples loading schemes. Significantly greater total power output (21.6-25.1%) was observed for all interrepetition rest interventions when compared to traditional continuous 6RM total power output. No significant between-group differences were found (p = 0.96). We conclude that utilizing interrepetition rest intervals enables greater repetition and total power output in comparison to traditional loading parameters.
Interestingly Lawtons group saw significantly different total TUT when rest is inserted, IOW one can lift the same weight more times. Their study also showed how rest impacted metabolites.
In Wernbom's excellent review (Sports Med. 2007;37(3):225-64.), he points to an unpublished study which had one of the largest CSA changes seen and in that study there was inserted rest after each rep.
So again I don't think it is truly the metabolic constituents that are that important or rather they aren't nearly as important as time to peak recruitment, and time under peak recruitment.
