Thomas Swensen

Impact of resistance training on endurance performance. A new form of cross-training?

SummaryIn accordance with the principles of training specificity, resistance and endurance training induce distinct muscular adaptations. Endurance training, for example, decreases the activity of the glycolytic enzymes, but increases intramuscular substrate stores, oxidative enzyme activities, and capillary, as well as mitochondrial, density. In contrast, resistance or strength training reduces mitochondrial density, while marginally impacting capillary density, metabolic enzyme activities and intramuscular substrate stores (except muscle glycogen). The training modalities do induce one common muscular adaptation: they transform type IIb myofibres into IIa myofibres. This transformation is coupled with opposite changes in fibre size (resistance training increases, and endurance training decreases, fibre size), and, in general, myofibre contractile properties. As a result of these distinct muscular adaptations, endurance training facilitates aerobic processes, whereas resistance training increases muscular strength and anaerobic power. Exercise performance data do not fit this paradigm, however, as they indicate that resistance training or the addition of resistance training to an ongoing endurance exercise regimen, including running or cycling, increases both short and long term endurance capacity in sedentary and trained individuals. Resistance training also appears to improve lactate threshold in untrained individuals during cycling. These improvements may be linked to the capacity of resistance training to alter myofibre size and contractile properties, adaptations that may increase muscular force production. In contrast to running and cycling, traditional dry land resistance training or combined swim and resistance training does not appear to enhance swimming performance in untrained individuals or competitive swimmers, despite substantially increasing upper body strength. Combined swim and swim-specific ‘in-water’ resistance training programmes, however, increase a competitive swimmer’s velocity over distances up to 200m. Traditional resistance training may be a valuable adjunct to the exercise programmes followed by endurance runners or cyclists, but not swimmers; these latter athletes need more specific forms of resistance training to realise performance improvement.

Methods for estimating the maximal lactate steady state in trained cyclists

PURPOSE Maximal lactate steady state (MLSS) is the highest exercise intensity at which blood lactate concentration (HLa) remains stable. In this study, we examined the validity of simulated 5-km and 40-km time trials (TT) as methods for estimating average speed at MLSS in cyclists. METHODS Nine trained cyclists reported to the laboratory for five to seven exercise trials. Testing included a VO2max test, a simulated 5-km and 40-km TT, and several 30-min MLSS trials. RESULTS Mean VO2peak was 4.42 +/- 0.13 L.min-1, whereas VO2 at MLSS (N = 8) was 3.54 +/- 0.15 L.min-1, representing 80.1 +/- 4.1% of VO2peak. HR and HLa at MLSS were 174.7 +/- 2.6 b.min-1 and 6.9 +/- 0.8 mM, respectively. MLSS speed was 36.8 +/- 1.0 km.h-1, which corresponded to 92.1 +/- 1.2% of 5 km average speed (AVS5km). Mean AVS, HLa, and HR during the 40-km TT were 36.6 +/- 0.9 km.h-1, 6.3 +/- 0.7 mM, and 174.1 +/- 2.1 b.min-1, respectively, and did not differ from those at MLSS. CONCLUSIONS Both the (simulated) 5-km and 40-km TT can be used to estimate the MLSS in cyclists. In addition, HLa at MLSS shows a large degree of variation between riders.

Development and reliability of two core stability field tests.

Because of the recognized link between core stability and back and lower extremity injury in sport, additional field tests that assess the strength and power component of core stability are needed to identify athletes at risk of such injury. To that end, we developed and tested the reliability of the front and side abdominal power tests (FAPT and SAPT), which were adapted from plyometric medicine ball exercises. The FAPT and SAPT were performed by explosively contracting the core musculature using the arms as a lever to project a medicine ball. Twenty-four untrained young women (aged 20.9 ± 1.1 year) completed three trials each of the FAPT and SAPT on separate nonconsecutive days. The average distance the medicine ball was projected on each day was recorded; power was inferred from this measure. There was an approximately 3% increase in the mean distance between the testing sessions for the FAPT and SAPT; this was not significant and indicates there was no learning effect in the measurement protocol. Heteroscedasticity was present in the SAPT data but not the FAPT data. For the FAPT, the intraclass correlation coefficient was 0.95, standard error of measurement was 24 cm, and random error using the limits of agreement method was 67.5 cm. For the SAPT, the intraclass correlation coefficient was 0.93, mean coefficient of variation was 9.8%, and the limits of agreement ratio was 36.8%. The FAPT and SAPT displayed excellent test-retest reliability, as well as acceptable measurement error. These findings suggest the FAPT and SAPT are reliable tests and may be used to assess the power component of core stability in young women.

Noninvasive estimation of the maximal lactate steady state in trained cyclists

PURPOSE The purposes of this study were to estimate noninvasively the maximal lactate steady state (MLSS) in trained cyclists on a windload simulator with a velocity based technique and to determine whether the HR at MLSS (HR(MLSS)) elicited a similar blood lactate concentration (BLC) during field testing. METHODS To determine and verify MLSS, 10 male cyclists performed five to seven laboratory trials on separate days, including a VO2max test; a 5-km time trial (TT); and two or more 30-min trials at specific percentages of each subjects average 5-km TT speed (AVS5km). Mean+/-SD for the following variables were obtained at MLSS: velocity was 90.3+/-2.7% of the AVS5km, BLC was 5.4+/-1.6 mM, RPE was 15+/-2.1, VO2 was 80+/-6.3% of VO2max, and HR was 167+/-9.5 beats x min(-1), which was 88+/-3.8% of the mean maximum HR. Field tests included three laps of an 8-km road circuit at HR(MLSS) +/-3 beats x min(-1) and one lap at maximum sustainable velocity (a road TT). RESULTS There were no significant differences in BLC, HR, and RPE between the three steady-state road laps and the lab MLSS trial. There was also good agreement between the road and lab MLSS velocity/TT velocity ratios. CONCLUSIONS Our data suggest that 5-km TT cycling velocity, as measured on a windload simulator, may be used to estimate MLSS and the HR at MLSS for training purposes.

Age, Weight, and the Front Abdominal Power Test as Predictors of Isokinetic Trunk Strength and Work in Young Men and Women.

Cowley, PM, Fitzgerald, S, Sottung, K, and Swensen, T. Age, weight, and the front abdominal power test as predictors of isokinetic trunk strength and work in young men and women. J Strength Cond Res 23(3): 915-925, 2009-First we tested the reliability of two new field tests of core stability (plank to fatigue test [PFT] and front abdominal power test [FAPT]), as well as established measures of core stability (isokinetic trunk extension and flexion strength [TES and TFS] and work [TEW and TFW]) over 3 days in 8 young men and women (24.0 ± 3.1 years). The TES, TFS, TFW, and FAPT were highly reliable, TEW was moderately reliable, and PFT were unreliable for use during a single testing session. Next, we determined if age, weight, and the data from the reliable field test (FAPT) were predictive of TES, TEW, TFS, and TFW in 50 young men and women (19.0 ± 1.2 years). The FAPT was the only significant predictor of TES and TEW in young women, explaining 16 and 15% of the variance in trunk performance, respectively. Weight was the only significant predictor of TFS and TFW in young women, explaining 28 and 14% of the variance in trunk performance, respectively. In young men, weight was the only significant predictor of TES, TEW, TFS, and TFW, and explained 27, 35, 42, and 33%, respectively, of the variance in trunk performance. In conclusion, the ability of weight and the FAPT to predict TES, TEW, TFS, and TFW was more frequent in young men than women. Additionally, because the FAPT requires few pieces of equipment, is fast to administer, and predicts isokinetic TES and TEW in young women, it can be used to provide a field-based estimate of isokinetic TES and TEW in women without history of back or lower-extremity injury.

Factors affecting the oxygen cost of stepping on an electronic stepping ergometer

The purposes of this study were to evaluate (a) the effects of step rate and upper body support on the VO2 and HR responses to fixed work rates on the StairMaster 4000 (SM), (b) the accuracy of the SM settings, and (c) how HR compared with that measured during grade-walking on a treadmill. Six subjects worked at a slow step rate for 6 min and then a faster step rate for the last 6 min of a 12-min test at SM settings of 4, 7, and 10 METs. Gas exchange and HR measurements were made at minutes 4-6 and 10-12. Variations in step rate had no effect on HR (P = 0.45) or VO2 (P = 0.84). The effect of using the arms and hands for support was studied using 6 subjects who worked for 12 min at 4, 7, and 10 METs; the first 6 min without support, and the second 6 min with support. Support resulted in lower HR (P = 0.017) and VO2 (P = 0.002) values at 10 METs. The measured MET values were about 20% lower than those specified by machine settings: True MET values = 0.556 + 0.745 (SM setting). Finally, at the same VO2, systematically higher (7-11 b.min-1) HR values were observed for the SM relative to the treadmill.

Effect of betaine supplementation on cycling sprint performance

PurposeTo examine the effect of betaine supplementation on cycling sprint performance.MethodsSixteen recreationally active subjects (7 females and 9 males) completed three sprint tests, each consisting of four 12 sec efforts against a resistance equal to 5.5% of body weight; efforts were separated by 2.5 min of cycling at zero resistance. Test one established baseline; test two and three were preceded by seven days of daily consumption of 591 ml of a carbohydrate-electrolyte beverage as a placebo or a carbohydrate-electrolyte beverage containing 0.42% betaine (approximately 2.5 grams of betaine a day); half the beverage was consumed in the morning and the other half in the afternoon. We used a double blind random order cross-over design; there was a 3 wk washout between trials two and three. Average and maximum peak and mean power were analyzed with one-way repeated measures ANOVA and, where indicated, a Student Newman-Keuls.ResultsCompared to baseline, betaine ingestion increased average peak power (6.4%; p < 0.001), maximum peak power (5.7%; p < 0.001), average mean power (5.4%; p = 0.004), and maximum mean power (4.4%; p = 0.004) for all subjects combined. Compared to placebo, betaine ingestion significantly increased average peak power (3.4%; p = 0.026), maximum peak power max (3.8%; p = 0.007), average mean power (3.3%; p = 0.034), and maximum mean power (3.5%; p = 0.011) for all subjects combined. There were no differences between the placebo and baseline trials.ConclusionsOne week of betaine ingestion improved cycling sprint power in recreationally active males and females.

Derivation of prediction equations for RV in overweight men and women.

PURPOSE The purpose of this research was to derive and compare regression equations for predicting residual volume (RV) in overweight and normal weight adults. METHODS RV was determined on land, in 311 men and women, following an overnight fast, using the nitrogen-dilution technique. Subjects were then weighed underwater at RV; 5-10 underwater weights were recorded; and the heaviest 3 measurements were averaged as the underwater weight. Percent body fat was calculated using the Siri equation. Group analyses were performed on overweight men (N = 59, body fat > 25%) and women (N = 126, body fat > 30%) compared with normal weight men (N = 68, body fat < or = 25%) and women (N = 58, body fat < or = 30%). A stepwise regression was performed for each group using the Systat Statistical Package (Evanston, IL). RESULTS When RV was regressed on sex, age (yr), body weight (kg), and height (cm), sex was not found to be a significant predictor variable for RV. Subsequent regressions revealed that prediction equations for the overweight (RV = 0.0277 AGE + 0.0048 WT + 0.0138 HT - 2.3967, F = 44.0, P < 0.0000, SEE = 0.403) were different from those generated for normal weight men and women (RV = 0.0275 AGE + 0.0189 HT - 2.6139, F = 58.6, P < 0.0000, SEE = 0.405). Similar equations were obtained when a cross validation was performed on a separate sample of normal weight (N = 31) and overweight (N = 46) men and women. CONCLUSION These data suggest that prediction equations for RV are separate and distinct for the overweight and normal weight populations.

THE EFFECTS OF MASSAGE ON DELAYED ONSET MUSCLE SORENESS

OBJECTIVES The purpose of this study was to investigate the physiological and psychological effects of massage on delayed onset muscle soreness (DOMS). METHODS Eighteen volunteers were randomly assigned to either a massage or control group. DOMS was induced with six sets of eight maximal eccentric contractions of the right hamstring, which were followed 2 h later by 20 min of massage or sham massage (control). Peak torque and mood were assessed at 2, 6, 24, and 48 h postexercise. Range of motion (ROM) and intensity and unpleasantness of soreness were assessed at 6, 24, and 48 h postexercise. Neutrophil count was assessed at 6 and 24 h postexercise. RESULTS A two factor ANOVA (treatment v time) with repeated measures on the second factor showed no significant treatment differences for peak torque, ROM, neutrophils, unpleasantness of soreness, and mood (p > 0.05). The intensity of soreness, however, was significantly lower in the massage group relative to the control group at 48 h postexercise (p < 0.05). CONCLUSIONS Massage administered 2 h after exercise induced muscle injury did not improve hamstring function but did reduce the intensity of soreness 48 h after muscle insult.

Effect Of L-citrulline On Muscle Recovery After Anaerobic And Aerobic Exercise: 3288 Board #49 May 30, 9

PURPOSE: Previous research shows that acute L-citrulline supplementation improves anaerobic performance and reduces muscle soreness, suggesting it may improve muscle recovery following exercise. With a double blind crossover design, we evaluated the acute effect of L-citrulline supplementation on muscle recovery and cycling sprint and 2 mi time trial (TT) performance. METHODS: 22 college students (19.5 ± 1.3 y) completed a preliminary cycling VO2 max test (43.2 ± 10.8 ml.kg .min -1 ) and were then twice familiarized with the sprint test (4 x 12 s sprints at 5.5% of body mass, separated by 2.5 min of active recovery) and the TT; testing sessions were separated by 48 h. Approximately 5 d later and 1 hr before repeating the tests, 11 subjects consumed 6 g of citrulline, while the other 11 ingested 6 g of a cornstarch placebo; to assess recovery, the tests were repeated 24 hr later. After a 1 wk washout, subjects repeated the tests with the other treatment. Data were analyzed with twoway repeated measures ANOVA; where indicated, specific differences were located with Bonferroni postas set at 0.05. RESULTS: Table 1 shows mean power in watts (W) for maximum peak power (MPP), average peak power (APP), maximum mean power (MMP), and average mean power (AMP) for the sprint tests, and mean time in seconds and power (W) for the TT. CONCLUSION: The data show that citrulline did not improve any measure of performance or muscle recovery. Indeed, it decreased TT performance relative to the placebo. In contrast, 6 g or 24 kcal of cornstarch ingested 1 h before exercise improved sprint performance 24 h after a bout of similar exercise. Table 1.