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Ghanbari-Niaki A, Abednazari H, Tayebi SM, Hossaini-Kakhak A, Kraemer RR. Treadmill training enhances rat agouti-related protein in plasma and reduces ghrelin levels in plasma and soleus muscle. Metabolism 2009; 58:1747-52. [PMID: 19632697 DOI: 10.1016/j.metabol.2009.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 06/03/2009] [Accepted: 06/16/2009] [Indexed: 11/26/2022]
Abstract
Ghrelin and agouti-related protein (AgRP) are orexigenic peptides secreted from stomach mucosa and the arcuate nucleus of the hypothalamus, respectively. Both peptides affect feeding behavior and play a role in energy balance, glucose homeostasis, and adiposity. The purpose of the current study was to determine the effects of moderate-term (6 weeks) running regimen on resting levels of ghrelin, AgRP, adenosine triphosphate, and glycogen in soleus muscle as well as plasma concentrations of the orexigenic hormones. Eighteen adult Wistar male rats (12 weeks old, 235-255 g) were randomly assigned to training (n = 10) and control (n = 8) groups. The training group ran for 60 min/d, 5d/wk at 25 m/min and 0% grade for 6 weeks. Forty-eight hours after the last exercise session, rats were killed; and soleus muscle and plasma were collected and frozen in liquid nitrogen for later analysis. Results demonstrated that 6 weeks of treadmill exercise reduced ghrelin and increased AgRP levels in plasma. Trained rat soleus muscle had higher levels of glycogen but not adenosine triphosphate or AgRP compared with untrained controls. Data indicate that training lowers ghrelin levels in rat soleus and plasma, which is accompanied by higher plasma AgRP and soleus glycogen content.
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Goto K, Ishii N, Kizuka T, Kraemer RR, Honda Y, Takamatsu K. Hormonal and metabolic responses to slow movement resistance exercise with different durations of concentric and eccentric actions. Eur J Appl Physiol 2009; 106:731-9. [PMID: 19430944 DOI: 10.1007/s00421-009-1075-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/2009] [Indexed: 11/24/2022]
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Kilpatrick MW, Kraemer RR, Quigley EJ, Mears JL, Powers JM, Dedea AJ, Ferrer NF. Heart rate and metabolic responses to moderate-intensity aerobic exercise: a comparison of graded walking and ungraded jogging at a constant perceived exertion. J Sports Sci 2009; 27:509-16. [PMID: 19204846 DOI: 10.1080/02640410802668650] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
In this study, we assessed how ungraded jogging and graded walking at the same rating of perceived exertion (RPE) affect heart rate and oxygen consumption ([Vdot]O(2)). Twenty untrained participants completed a treadmill test to determine peak [Vdot]O(2) (mean = 40.3 +/- 6.3 ml . kg(-1) . min(-1)). Participants completed separate 30-min trials of moderate exercise (RPE of 13 on the Borg 6-20 scale) in random order on the treadmill: graded walking and ungraded jogging. Treadmill speed or grade was adjusted throughout the trial by the experimenter based on participant responses to maintain an RPE of 13. The jogging trial produced a significantly higher heart rate (161 +/- 18 vs. 142 +/- 24 beats . min(-1)) and [Vdot]O(2) (7.4 +/- 1.8 vs. 5.8 +/- 1.5 METs) (P < 0.01) than the walking trial. Treadmill grade decreased significantly during the walking trial (11.1 +/- 2.3% to 10.0 +/- 2.2%; P < 0.01), but treadmill speed did not change significantly during the jogging trial (5.2 +/- 1.0 miles . h(-1) to 5.0 +/- 0.9 miles . h(-1)) (P > 0.05), in an effort to maintain constant RPE. These findings provide evidence that similar perceptions of effort during graded walking and ungraded jogging do not produce similar cardiovascular and metabolic responses. The results indicate that, for a given prescribed perceived effort, jogging provides a greater stimulus for fitness benefits and caloric expenditure.
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Kraemer RR. How Does my Stomach Know What my Muscles Need? Effect of Exercise on Hunger/Satiety Hormones. Med Sci Sports Exerc 2009. [DOI: 10.1249/01.mss.0000352657.30866.2b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ortego AR, Dantzler DK, Zaloudek A, Tanner J, Khan T, Panwar R, Hollander DB, Kraemer RR. Effects of Gender on Physiological Responses to Strenuous Circuit Resistance Exercise and Recovery. J Strength Cond Res 2009; 23:932-8. [DOI: 10.1519/jsc.0b013e3181a07884] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Manshouri M, Ghanbari-Niaki A, Kraemer RR, Shemshaki A. Time course alterations of plasma obestatin and growth hormone levels in response to short-term anaerobic exercise training in college women. Appl Physiol Nutr Metab 2009; 33:1246-9. [PMID: 19088784 DOI: 10.1139/h08-098] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Obestatin is a 23-amino-acid peptide encoded by the same gene as ghrelin. Because there is a paucity of data concerning the effects of exercise on obestatin, this study investigated the effect of anaerobic exercise training-detraining on obestatin and growth hormone (GH) plasma levels. Ten young female volunteers participated. Blood was collected 24 h before, and 24 h, 48 h and 7 days after the training. The data indicate that anaerobic training caused a significant reduction in GH levels but had no effect on plasma obestatin concentrations.
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Hollander DB, Kilpatrick MW, Ramadan ZG, Reeves GV, Francois M, Blakeney A, Castracane VD, Kraemer RR. Load Rather Than Contraction Type Influences Rate of Perceived Exertion and Pain. J Strength Cond Res 2008; 22:1184-93. [DOI: 10.1519/jsc.0b013e31816a8bc2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kraemer RR, Ortego A, Dantzler D, Zaloudek A, Jamie T, Tahir K, Pawar R, Hollander DB. Effects of Gender on Physiological Responses to Strenuous Circuit Resistance Exercise and Recovery. Med Sci Sports Exerc 2008. [DOI: 10.1249/01.mss.0000323157.66532.d9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Garten RS, Kraemer RR, Cho C, Chee P, Reeves GV, Hollander DB, Thomas C, Francois M, Goldfarb AH. Resistance Exercise Effects on Blood Protein Carbonyls and Glutathione Status: Influence of Partial Vascular Occlusion. Med Sci Sports Exerc 2008. [DOI: 10.1249/01.mss.0000323077.16738.b5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hollander DB, Kraemer RR, Kilpatrick MW, Ramadan ZG, Reeves GV, Francois M, Hebert EP, Tryniecki JL. Maximal eccentric and concentric strength discrepancies between young men and women for dynamic resistance exercise. J Strength Cond Res 2007; 21:34-40. [PMID: 17313264 DOI: 10.1519/r-18725.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although research has demonstrated that isokinetic eccentric (ECC) strength is 20-60% greater than isokinetic concentric (CON) strength, few data exist comparing these strength differences in standard dynamic resistance exercises. The purpose of the study was to determine the difference in maximal dynamic ECC and CON strength for 6 different resistance exercises in young men and women. Ten healthy young men (mean +/- SE, 25.30 +/- 1.34 years), and 10 healthy young women (mean +/- SE, 23.40 +/- 1.37 years) who were regular exercisers with resistance training experience participated in the study. Two sessions were performed to determine CON and ECC 1 repetitions maximum for latissimus pull-down (LTP), leg press (LP), bench press (BP), leg extension (LE), seated military press (MP), and leg curl (LC) exercises. Maximal ECC and maximal CON strength were determined on weight stack machines modified to isolate ECC and CON contractions using steel bars and pulleys such that only 1 type of contraction was performed. Within 2 weeks, participants returned and completed a retest trial in a counterbalanced fashioned. Test-retest reliability was excellent (r = 0.99) for all resistance exercise trials. Men demonstrated 20-60% greater ECC than CON strength (LTP = 32%, LP = 44%, BP = 40%, LE = 35%, MP = 49%, LC = 27%). Women's strength exceeded the proposed parameters for greater ECC strength in 4 exercises, p < 0.05 (LP = 66%, BP = 146%, MP = 161%, LC = 82%). The ECC/CON assessment could help coaches capitalize on muscle strength differences in young men and women during training to aid in program design and injury prevention and to enhance strength development.
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Acevedo EO, Kraemer RR, Kamimori GH, Durand RJ, Johnson LG, Castracane VD. STRESS HORMONES,EFFORT SENSE, AND PERCEPTIONS OF STRESS DURING INCREMENTAL EXERCISE. J Strength Cond Res 2007; 21:283-8. [PMID: 17313283 DOI: 10.1519/00124278-200702000-00050] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Exercise elicits intensity-dependent increases in epinephrine (Epi), norepinephrine (NE), cortisol (CORT), and lactate (Lac), whereas at rest the hormonal responses to mental stress include increases in Epi, NE, and CORT, but not Lac. Additionally, elevations in CORT at rest are associated with negative affect. Finally, as exercise intensity increases, perceptions of effort (RPE) increase and affect becomes more negative. The purpose of this study was to examine the responses of Epi, NE, CORT, Lac, RPE, and affect during incremental increases in exercise to maximum. Seven highly-trained male runners completed a discontinuous treadmill protocol that included 10 minutes at 60%, 10 minutes at 75%, 5 minutes at 90%, and 2 minutes at 100% of VO2max. Blood samples were collected through an intravenous catheter before, during, and following exercise during the experimental condition, and during a time-matched control condition. RPE and affect were assessed just prior to each blood draw. The Epi, NE, CORT, and Lac displayed the expected incremental increases, however affect became more negative at higher exercise intensities, and RPE increased as exercise intensity increased. Data suggest that CORT follows the same pattern of response to graded exercise as affect. Since perceptual and affective responses to exercise are associated with motivation, these documented negative affective shifts during exercise should be considered in order to develop strategies that lead to enhanced exercise adherence and performance.
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Kraemer RR, Castracane VD. Exercise and humoral mediators of peripheral energy balance: ghrelin and adiponectin. Exp Biol Med (Maywood) 2007; 232:184-94. [PMID: 17259325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023] Open
Abstract
Ghrelin and adiponectin are recently discovered peptides that are both associated with energy homeostasis and insulin action. In addition, circulating levels of both peptides are altered in obese populations and are associated with poor health. Moreover, expression of ghrelin and adiponectin returns to normal levels following weight loss in obese patients. Because exercise training improves the health status of obese individuals and is associated with reduction of body weight, there is interest in the effects of exercise on adiponectin and ghrelin and whether these peptides may provide better understanding of how exercise improves health. Ghrelin levels do not increase in response to acute running and cycling in humans, and therefore ghrelin does not appear to regulate growth hormone (GH) release during exercise. There is some evidence that ghrelin levels are suppressed following resistance exercise of moderate intensity and are lower with higher GH concentrations during aerobic exercise. It has been suggested that negative feedback from elevated GH produces the reductions, but why these responses have not been consistently found in other studies and whether postexercise reduction in ghrelin affects appetite warrants further investigation. There are a few studies (but not all) that suggest long-term chronic exercise produces increases in ghrelin levels when weight loss is produced. Ghrelin levels are much higher in amenorrheic athletes than in ovulating exercisers or in female exercisers with a luteal phase defect, suggesting an association with reproductive function. Adiponectin concentrations do not change in response to moderate and strenuous running or low- and moderate- intensity cycling. Most studies have revealed that chronic exercise that improves fitness levels, increases insulin sensitivity, and reduces body weight, will increase resting adiponectin levels. However, it does not appear that changes in insulin sensitivity brought about by moderate exercise training are attributable to adiponectin.
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Reeves GV, Kraemer RR, Hollander DB, Clavier J, Thomas C, Francois M, Castracane VD. Comparison of hormone responses following light resistance exercise with partial vascular occlusion and moderately difficult resistance exercise without occlusion. J Appl Physiol (1985) 2006; 101:1616-22. [PMID: 16902061 DOI: 10.1152/japplphysiol.00440.2006] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous studies of contracting muscle with low loading and partial vascular occlusion demonstrated hypertrophy and strength adaptations similar to and exceeding those observed with traditional moderate to high resistance (Shinohara M, Kouzaki M, Yoshihisa T, and Fukunaga T. Eur J Physiol 77: 189-191, 1998; Takarada Y, Takazawa H, Sato Y, Takebayashi S, Tanaka Y, and Ishii N. J Appl Physiol 88: 2097-2106, 2000; Takarada Y, Sato Y, and Ishii N. Eur J Physiol 86: 308-314, 2002). The purpose of the study was to determine the anabolic and catabolic hormone responses to light resistance exercise combined with partial vascular occlusion. Three experimental conditions of light resistance with partial occlusion (LRO), moderate resistance with no occlusion (MR), and partial occlusion without exercise (OO) were performed by eight healthy subjects [mean 21 yr (SD 1.8)]. Three sets of single-arm biceps curls and single-leg calf presses were completed to failure with 1-min interset rest periods. Workloads of 30 and 70% one repetition maximum for each exercise were lifted for the LRO and MR trials, respectively. Blood samples were taken preexercise, postexercise, and 15 min postexercise for each experimental condition. Lactate increased significantly in the LRO and MR trials and was not significantly different from each other at any time point. Growth hormone (GH) increased significantly by fourfold from pre- to postexercise in the LRO session but did not change significantly during this time period in the MR and OO trials (8.3 +/- 2.3 vs. 2.1 +/- 1.2 and 2.6 +/- 0.94 microg/l; respectively, P < 0.05). There were no changes in resting total testosterone [T; mean 15.7 +/- 1.6 (SE) nmol/l], free testosterone (FT; 54.1 +/- 4.5 pmol/l), or cortisol (267.6 +/- 22 nmol/l) across all trials and times. In conclusion, with similar lactate responses, light exercise combined with partial vascular occlusion elicits a greater GH response than moderate exercise without occlusion but does not affect T, FT, or cortisol.
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Jeansonne JJ, West VA, Hoenig JR, Kraemer RR, Hebert EP. Effects of a Short Duration Jump Training Program on Collegiate and Recreational Female Athletes. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200605001-02560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hollander DB, Reeves GV, Kraemer RR, Clavier JD, Francois M, Jeansonne JJ, Tryniecki J, Kraemer RR. Partial Vascular Occlusion Significantly Altered RPE, Pain, and Lactate during Resistance Exercise. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200605001-02977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Goto K, Ishii N, Sugihara S, Yoshioka T, Takamatsu K, Kraemer RR. The Effects of Prior Resistance Exercise on Lipolysis and Fat Oxidation during Subsequent Endurance Exercise. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200605001-03144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Reeves GV, Kraemer RR, Hollander DB, Clavier JD, Thomas CA, Francois MR, Castracane VD. Hormonal Responses to Resistance Exercise with Partial Vascular Occlusion. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200605001-02904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Castracane VD, Kraemer GR, Ogden BW, Kraemer RR. Interrelationships of serum estradiol, estrone, and estrone sulfate, adiposity, biochemical bone markers, and leptin in post-menopausal women. Maturitas 2006; 53:217-25. [PMID: 15913927 DOI: 10.1016/j.maturitas.2005.04.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2004] [Revised: 04/06/2005] [Accepted: 04/11/2005] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The aim of this study was to examine the relationships between endogenous estrogens and adiposity, bone markers, and leptin in post-menopausal (PM) women. DESIGN Seventy-three post-menopausal (PM) women participated in a clinical correlational study. Weight, height, waist-hip ratio, fasted morning serum and first morning voided urine samples were obtained to compare body mass index (BMI), waist-hip ratio, endogenous estrogens, leptin, and bone markers. Serum estradiol, estrone (E1), estrone sulfate (E1S), leptin, osteocalcin, and urinary deoxypyridinoline (Dpd) were determined. RESULTS Significant positive relationships were found between BMI and estradiol, E1, and E1S (r = 0.52, 0.38, and 0.29; P < or = 0.001, 0.001, and 0.013 respectively). Significant relationships between leptin and estrogens were revealed, but were not significant when BMI was used as a covariate. Although many subjects revealed elevated bone marker levels, no correlation between estrogens or BMI and bone markers (Dpd and osteocalcin) was found. CONCLUSIONS There are significant positive correlations between estrogens and BMI in PM women. Increasing levels of estradiol, E1, and E1S with increasing BMI may be an indicator of adiposity, but are without effect as a stimulatory factor on leptin production. Waist-hip ratio did not significantly affect leptin concentrations when accounting for BMI. Due to assay sensitivity in the present study, data represent a more precise representation of these relationships. The lack of correlation between estrogens and bone marker levels may have been due to low estrogen levels in PM women.
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Kraemer RR, Hollander DB, Reeves GV, Francois M, Ramadan ZG, Meeker B, Tryniecki JL, Hebert EP, Castracane VD. Similar hormonal responses to concentric and eccentric muscle actions using relative loading. Eur J Appl Physiol 2005; 96:551-7. [PMID: 16369814 DOI: 10.1007/s00421-005-0094-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2005] [Indexed: 11/24/2022]
Abstract
Conventional resistance exercise is performed using sequential concentric (CON) and eccentric (ECC) contractions, utilizing the same muscle load. Thus, relative to maximal CON and ECC resistance, the ECC contraction is loaded to a lesser degree. We have recently shown that at the same absolute load, CON contractions are associated with greater growth hormone (GH) but similar total testosterone (TT) and free testosterone (FT) responses compared with ECC contractions and attributed the larger GH response to greater relative CON loading. In the present study, we have examined the same endocrine parameters to six different upper and lower body exercises using relative loading rather than absolute loading, hypothesizing that GH responses would be similar for CON and ECC actions, but TT and FT responses would be greater after ECC contractions. Seven young men with recreational weight training experience completed an ECC and CON muscle contraction trial on two different occasions in a counterbalanced fashion. The exercises consisted of four sets of 10 repetitions of lat pull-down, leg press, bench press, leg extension, military press, and leg curl exercises at 65% of an ECC or CON 1-RM with 90 s between sets and exercises. CON and ECC actions were performed at the same speed. ECC 1-RMs were considered to be 120% of the CON 1-RM for the same exercise. Blood samples were collected before, immediately after, and 15 min after the exercise. GH significantly increased across both trials but was not different between the two trials. Total testosterone was not significantly altered in response to either trial; however, free testosterone concentrations increased in response to both ECC and CON trials. Data suggest that CON and ECC muscle contractions produce similar GH, T, and free testosterone responses with the same relative loading.
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Hollander DB, Kraemer RR, Kilpatrick MW, Reeves GV, Ramadan Z, Francois M, Tryniecki JL, Castracane VD. Comparing Perceptual, Cardiac And Hormonal Markers Of Relative Loads On Eccentric Versus Concentric Resistance Exercises. Med Sci Sports Exerc 2005. [DOI: 10.1249/00005768-200505001-01655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kraemer RR, Hollander DB, Reeves GV, Ramadan ZG, Francois M, Tryniecki JL, Kilpatrick M, Castracane VD. Growth Hormone And Testosterone Responses To Relative Loading Of Concentric And Eccentric Muscle Actions. Med Sci Sports Exerc 2005. [DOI: 10.1249/00005768-200505001-01239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kraemer RR, Durand RJ, Hollander DB, Tryniecki JL, Hebert EP, Castracane VD. Ghrelin and other glucoregulatory hormone responses to eccentric and concentric muscle contractions. Endocrine 2004; 24:93-8. [PMID: 15249708 DOI: 10.1385/endo:24:1:093] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2004] [Revised: 05/11/2004] [Accepted: 05/13/2004] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Heavy resistance exercise increases growth hormone (GH) and blood glucose levels. Ghrelin is an endogenous ligand for the GH secretagory receptor that stimulates growth hormone release. Circulating ghrelin levels are suppressed by insulin and glucose. The study was conducted to determine effects of concentric (CON) and eccentric (ECC) muscle actions at the same absolute workload on circulating ghrelin and glucose as well as related glucoregulatory peptides. METHODS Ten-RM loads for bench press, leg extension, military press, and leg curl were obtained from nine males, mean age 25. +/- 1.2 yr and body fat 17.2 +/- 1.6%. Subjects then completed two experimental trials of either CON or ECC contractions at the same absolute workload. Subjects performed four sets of 12 repetitions for each exercise at 80% of a 10-RM with 90 s rest periods. A pulley system or steel levers were positioned on each machine to raise or lower the weight so only CON or ECC contractions were performed. Pre-, post-, and 15-min post-exercise blood samples were collected. RESULTS Ghrelin did not increase in response to either muscle action and actually declined during the CON trial. Glucose and insulin increased regardless of the form of muscle action, but amylin and C-peptide did not change. CONCLUSIONS Data indicate that ghrelin does not contribute to moderate resistance exercise-induced increases in growth hormone, whether from CON or ECC muscle actions. Results suggest that with a moderate loading protocol both CON and ECC muscle actions performed at the same absolute workload elevate glucose and insulin concentrations, but are not related to post-CON exercise ghrelin suppression.
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Hollander DB, Kraemer RR, Kilpatrick MW, Ramadan ZG, Reeves GW, Francois M, Durand RJ, Tryniecki JT. Eccentric and Concentric Strength Differences in Men and Women. Med Sci Sports Exerc 2004. [DOI: 10.1249/00005768-200405001-01684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Acevedo EO, Kraemer RR, Haltom RW, Tryniecki JL. Percentual responses proximal to the onset of blood lactate accumulation. J Sports Med Phys Fitness 2003; 43:267-73. [PMID: 14625505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
AIM Running at incremental velocities proximal to the onset of blood lactate accumulation (OBLA) elicits linear increases in VO(2), and HR, while the increases in V(E) and blood lactic acid concentrations (BLa) are curvilinear. In addition, effort sense is often measured in the field with the traditional 15-point scale Ratings of Perceived Exertion scale, increases linearly whereas the perceptual response of affect seem to decrease in a nonlinear manner. This study examined the changes in effort sense (RPE) and affect, utilizing the Feeling Scale (FS), at 3 running intensities proximal to the onset of blood lactate accumulation. In addition, the relationship between these perceptual responses and V(E), VO(2), HR, RER, and BLa were examined. METHODS Eleven highly-trained distance runners (VO(2max) = 67.65+/-1.24) participated in 2 sessions of data collection. During Session 1 subjects performed a discontinuous progressive treadmill protocol to determine peak aerobic power. After each stage a finger tip blood sample was taken to determine BLa. A regression line between the 2 successive workloads that produced BLa above and below 4 mM was calculated to predict the VO(2) that would generate 4mM BLa (VO(2) @ 4 mM). Within 1 week each subject returned for Session 2, which included a 10-min warm-up run followed by 3 submaximal runs lasting 5 min each: the VO(2) at 10% below OBLA (VO(2) 10% ), the VO(2) at OBLA (VO(2) @ 4 mM), and the VO(2) at 10% above OBLA (VO(2) 10%). During the last minute of each run VO(2), V(E), HR, RER, RPE, and FS were assessed. In addition, Bla was assessed immediately following each run. RESULTS Results demonstrated that VO(2) 10%, VO(2) @ 4 mM, and VO(2) 10% - elicited BLa of 2.66+/-0.33, 3.75+/-0.40, and 6.10+/-0.68 mM, respectively. In addition, RPE increased significantly from VO(2) 10% to VO(2) @ 4 mM and from VO(2) @ 4 mM to VO(2) 10% -; whereas FS demonstrated a slight decrease from VO(2) 10% to VO(2) @ 4 mM, and a more substantial and significant decrease from VO(2) @ 4 mM to VO(2) 10% -. Correlational analyses revealed significant relationships at VO(2) 10% -. Specifically, RPE and FS were negatively related (r=0.62), while RPE and VO(2) were positively related (r=0.53). Correlations across all workloads revealed a tendency for more powerful relationships to exist among RPE and physiological cues than FS and physiological cues. CONCLUSION This is the first study to directly examine changes in RPE and FS in relation to the physiological threshold for anaerobic metabolism, Bla, which responds to linear increases in exercise intensity in a curvilinear manner. Results support previous investigations suggesting a that the drop in FS has some distinction from the increase in RPE and that FS may be more sensitive to the onset of anaerobic metabolism. Moreover, the relationship of RPE to FS at VO(2) 10% -, but not VO(2) 10% and VO(2) @ 4 mM, supports the hypothesis that the unique variability of FS is diminished at higher intensities of exercise when physiological cues are unambiguous.
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Shim J, Acevedo EO, Kraemer RR, Haltom RW, Tryniecki JL. Kinematic changes at intensities proximal to onset of lactate accumulation. J Sports Med Phys Fitness 2003; 43:274-8. [PMID: 14625506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
AIM The purpose of this study was to examine changes in selected kinematic variables at 3 running intensities proximal to the onset of blood lactate accumulation (OBLA; 4 mM of blood lactate). It was hypothesized that greater changes in lower body mechanics would occur when running faster than normal race pace compared to when running slower than race pace. METHODS Nine competitive male distance runners ran at 3 running intensities (RI): 1) each runner's VO(2) at 10% below the VO(2) at OBLA, 2) VO(2) at OBLA, and 3) VO(2) at 10% above the VO(2) at OBLA. Selected kinematic and physiological variables were measured at each RI. RESULTS VO(2) at RI 1, 2 and 3 was highly correlated with running speed (r=0.93). The blood lactate (BL) showed a nonlinear increase from RI 1 (2.9+/-0.8 mM) to 2 (4.1+/-0.9 mM) to 3 (6.7+/-1.8 mM). The vertical oscillation of center of gravity (VOCOG), stride frequency (SF), range of motion (ROM) of trunk angle, and maximal knee flexion during flight phase (MKFF) changed nonlinearly as did the BL. Significant relationships between BL and VOCOG (r=0.44) and between BL and SF (r=0.51) were found (ps<0.05). CONCLUSION The findings show a possibility that lower body running mechanics have a relationship with BL.
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