***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Summary A 28-week resistance training with linear periodization was compared with an undulating model in 27 premenopausal women . In both groups , bone mineral density ( BMD ) was not changed but muscle strength increased , and there were changes in anthropometrical and muscle damage parameters , indicating that in this population , these models are similar concerning these variables . Introduction This study seeks to compare the effects of resistance training with undulating versus linear periodization on BMD , muscle strength , anthropometrical variables , and muscle damage parameters in premenopausal women . Methods Twenty-seven females ( 39.6 ± 0.41 years , mean ± st and ard error ) , without osteopenia or osteoporosis and without calcium supplementation , were r and omly assigned either to a linear periodization group ( LPG , n = 14 ) or to an undulating periodization group ( UPG , n = 13 ) . The subjects were trained three times a week for 28 weeks . Lumbar spine and femoral neck BMDs were measured through dual-energy X-ray absorptiometry . Maximal and submaximal dynamic muscle strengths were measured through the 1-RM and 20-RM tests , respectively . Anthropometrical ( body mass , skinfolds , and perimeters ) and muscle damage parameters were assessed through serum creatine kinase ( CK ) and delayed-onset muscle soreness ( DOMS ) . Results BMD remained unchanged in both groups , despite significant increases in maximal ( LPG , 37–73 % ; UPG , 40–70 % ) and submaximal ( LPG , 82–114 % ; UPG , 70–102 % ) muscle strength . The perimeter of the distal thigh was increased ( about 1.7 cm ) in both groups . CK and DOMS were greater in the first mesocycle than in the subsequent ones . After the 1st training session in each mesocycle , 24 and 48 h CK was increased as compared to pretraining values . Conclusions The resistance training of 28 weeks increased muscle strength in both training groups with no difference in BMD or in the occurrence of muscle damage The purpose of the present investigation was to determine if significant differences exist among 3 different periodization programs in eliciting changes in strength .  Twenty-eight recreationally trained college-aged volunteers ( mean = SD ; 22.29 = 3.98 ) of both genders were tested for bench press , leg press , body fat percentage , chest circumference , and thigh circumference during initial testing . After initial testing , subjects were r and omly assigned to 1 of 3 training groups : ( a ) linear periodization ( n = 9 ) , ( b ) daily undulating periodization ( n = 10 ) , or ( c ) weekly undulating periodization ( n = 9 ) . The training regimen for each group consisted of a 9-week , 3-day-per-week program . Training loads were assigned as heavy ( 90 % , 4 repetition maximum [ 4RM ] ) , medium ( 85 % , 6RM ) , or light ( 80 % , 8RM ) for bench press and leg press exercises . Subjects were familiarized with the CR-10 rated perceived exertion scale and instructed to achieve an 8 or 9 on the final repetition of each set for all other exercises . Subjects were then retested after 4 weeks of training . Training loads were then adjusted according to the new 1RM . Subjects were then retested after 5 more weeks of exercise . For all subjects , significant ( p < 0.05 ) increases in bench press and leg press strength were demonstrated at all time points ( T1–T3 ) . No significant differences ( p > 0.05 ) were observed between groups for bench press , leg press , body fat percentage , chest circumference , or thigh circumference at all time points . These results indicate that no separation based on periodization model is seen in early-phase training Recently , the comparison of " periodized " strength training methods has been a focus of both exercise and sport science . Daily undulating periodization ( DUP ) , using daily alterations in repetitions , has been developed and touted as a superior method of training , while block forms of programming for periodization have been question ed . Therefore , the purpose of this study is to compare block to DUP in Division I track and field athletes . Thirty-one athletes were assigned to either a 10-wk block or DUP training group in which sex , year , and event were matched . Over the course of the study , there were 4 testing sessions , which were used to evaluate a variety of strength characteristics . Although performance trends favored the block group for strength and rate of force development , no statistically significant differences were found between the 2 training groups . However , statistically different ( P ≤ .05 ) values were found for estimated volume of work ( volume load ) and the amount of improvement per volume load between block and DUP groups . Based on calculated training efficiency scores , these data indicate that a block training model is more efficient than a DUP model in producing strength gains Abstract Simão , R , Spineti , J , de Salles , BF , Matta , T , Fern and es , L , Fleck , SJ , Rhea , MR , and Strom-Olsen , HE . Comparison between nonlinear and linear periodized resistance training : hypertrophic and strength effects . J Strength Cond Res 26(5 ) : 1389–1395 , 2012—The aim of this study was to investigate the effects of nonlinear periodized ( NLP ) and linear periodized ( LP ) resistance training ( RT ) on muscle thickness ( MT ) and strength , measured by an ultrasound technique and 1 repetition maximum ( 1RM ) , respectively . Thirty untrained men were r and omly assigned to 3 groups : NLP ( n = 11 , age : 30.2 ± 1.1 years , height : 173.6 ± 7.2 cm , weight : 79.5 ± 13.1 kg ) , LP ( n = 10 , age : 29.8 ± 1.9 years , height : 172.0 ± 6.8 cm , weight : 79.9 ± 10.6 kg ) , and  control group ( CG ; n = 9 , age : 25.9 ± 3.6 years , height : 171.2 ± 6.3 cm , weight : 73.9 ± 9.9 kg ) . The right biceps and triceps MT and 1RM strength for the exercises bench press ( BP ) , lat-pull down , triceps extension , and biceps curl ( BC ) were assessed before and after 12 weeks of training . The NLP program varied training biweekly during weeks 1–6 and on a daily basis during weeks 7–12 . The LP program followed a pattern of intensity and volume changes every 4 weeks . The CG did not engage in any RT . Posttraining , both trained groups presented significant 1RM strength gains in all exercises ( with the exception of the BP in LP ) . The 1RM of the NLP  group was significantly higher than LP for BP and BC posttraining . There were no significant differences in biceps and triceps MT between baseline and posttraining for any group ; however , posttraining , there were significant differences in biceps and triceps MT between NLP and the CG . The effect sizes were higher in NLP for the majority of observed variables . In conclusion , both LP and NLP are effective , but NLP may lead to greater gains in 1RM and MT over a 12-week training period Apel , JM , Lacy , RM , and Kell , RT . A comparison of traditional and weekly undulating periodized strength training programs with total volume and intensity equated . J Strength Cond Res 25(3 ) : 694 - 703 , 2011-The purpose of this study was to compare the training adaptations attained during 12 weeks of traditional ( TD ) and weekly undulating ( WUD ) periodized strength training .  Forty-two recreationally active men ( age = 22 ± 2.3 years ) were r and omly assigned to 1 of 3 groups : control ( C ) ( n = 14 ) , TD ( n = 14 ) , or WUD ( n = 14 ) . Ten-repetition maximum ( 10RM ) laboratory testing was carried out for the free weight back squat and the free weight flat bench press at baseline , week 8 , and week 12 . The subjects trained 3 d·wk−1 ( approximately 135 min·wk−1 ) from weeks 1 to 2 and 4 d·wk−1 from week 3 to week 12 ( approximately 180 min·wk−1 ) . The TD and WUD groups trained using a periodized strength program with all program variables controlled ( e.g. , volume and intensity ) . The independent variable was the manipulation of intensity . The TD group used a linear increase in intensity , whereas the WUD group had a varied intensity . The results showed that both the TD and WUD groups made significant ( p ≤ 0.05 ) increases in strength at weeks 8 and 12 , but by week 12 , the TD group was significantly ( p ≤ 0.05 ) stronger than the WUD group . These results indicate that TD periodization with a linear increase in intensity was more effective at eliciting strength gains than WUD periodization with a varied intensity . The differences in strength gains between the TD and WUD groups may be related to extended periods of muscle soreness and fatigue that were present in the WUD group but not in the TD group . Thus , during long-term training , individuals may benefit more from TD periodized programs because there may be less muscle soreness and fatigue to disrupt practice and training Monteiro , AG , Aoki , MS , Evangelista , AL , Alveno , DA , Monteiro , GA , Piçarro , IDC , and Ugrinowitsch , C. Nonlinear periodization maximizes strength gains in split resistance training routines . J Strength Cond Res 23(4 ) : 1321 - 1326 , 2009-The purpose of our study was to compare strength gains after 12 weeks of nonperiodized ( NP ) , linear periodized ( LP ) , and nonlinear periodized ( NLP ) resistance training models using split training routines . Twenty-seven strength-trained men were recruited and r and omly assigned to one of 3 balanced groups : NP , LP , and NLP . Strength gains in the  leg press  and in the  bench press exercises  were assessed . There were no differences between the training groups in the exercise pre-tests ( p > 0.05 ) ( i.e. , bench press and leg press ) . The NLP group was the only group to significantly increase maximum strength in the bench press throughout the 12-week training period . In this group , upper-body strength increased significantly from pre-training to 4 weeks ( p < 0.0001 ) , from 4 to 8 weeks ( p = 0.004 ) , and from 8 weeks to the post-training ( p < 0.02 ) . The NLP group also exhibited an increase in leg press 1 repetition maximum at each time point ( pre-training to 4 weeks , 4 - 8 week , and 8 weeks to post-training , p < 0.0001 ) . The LP group demonstrated strength increases only after the eight training week ( p = 0.02 ) . There were no further strength increases from the 8-week to the post-training test . The NP group showed no strength increments after the 12-week training period . No differences were observed in the anthropometric profiles among the training models . In summary , our data suggest that NLP was more effective in increasing both upper- and lower-body strength for trained subjects using split routines The purpose of this study was to compare linear periodization ( LP ) and daily undulating periodization ( DUP ) for strength gains . Twenty men ( age = 21 ± 2.3 years ) were r and omly assigned to LP ( n = 10 ) or  DUP  ( n = 10 ) groups . One repetition maximum ( 1RM ) was recorded for bench press and leg press as a pre- , mid- , and posttest . Training involved 3 sets ( bench press and leg press ) , 3 days per week . The LP group performed sets of 8 RM during weeks 1–4 , 6 RM during weeks 4–8 , and 4 RM during weeks 9–12 . The DUP group altered training on a daily basis ( Monday , 8 RM ; Wednesday , 6 RM ; Friday , 4 RM ) . Analysis of variance with repeated measures revealed statistically significant differences favoring the DUP group between T1 to T2 and T1 to T3 . Making program alterations on a daily basis was more effective in eliciting strength gains than doing so every 4 weeks The purpose of this study was to compare linear periodi-zation ( LP ) , daily undulating periodization ( DUP ) , and reverse linear periodization ( RLP ) for gains in local muscular endurance and strength .  Sixty subjects ( 30 men , 30 women ) were r and omly assigned to LP , DUP , or RLP groups . Maximal repetitions at 50 % of the subject 's body weight were recorded for leg extensions as a pretest , midtest , and post-test . Training involved 3 sets ( leg extensions ) 2 days per week . The LP group performed sets of 25 repetition maximum ( RM ) , 20RM , and 15RM changing every 5 weeks . The RLP group progressed in reverse order ( 15RM , 20RM , 25RM ) , changing every 5 weeks . The DUP group adjusted training variables between each workout ( 25RM , 20RM , 15RM repeated for the 15 weeks ) . Volume and intensity were equated for each training program . No significant differences were measured in endurance gains between groups ( RLP = 73 % , LP = 56 % , DUP = 55 % ; p = 0.58 ) . But effect sizes ( ES ) demonstrated that the RLP treatment ( ES = 0.27 ) was more effective than the LP treatment ( control ) and the DUP treatment ( ES = -0.02 ) at increasing muscular endurance . Therefore , it was concluded that making gradual increases in volume and gradual decreases in intensity was the most effective program for increasing 
    Output:
    
The meta-analyses determined that there were no differences in the effectiveness of linear vs. undulating periodization on upper-body or lower-body strength .
The results suggest that novelty or training variety are important for stimulating further strength development .
Few studies have examined the effect of periodization approaches in adolescent or athletic population