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  • Author: Jeremy P. Loenneke x
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Paul D. Loprinzi and Jeremy P. Loenneke

Objective:

Examine the association between grip strength and type 2 diabetes prevalence and severity.

Methods:

Using data from NHANES 2011–2012, objectively-determined hand grip strength was assessed using the Takei digital grip strength dynamometer, with diabetes assessed via physician diagnosis and glycohemoglobin A1C.

Results:

A 5 kg greater grip strength was associated with a 14% lower odds of having diabetes for men (ORadjusted = 0.86; 95% CI: 0.79 to 0.94; P = .002). Similarly, for women, a 5 kg greater grip strength was associated with an 18% lower odds of having diabetes (ORadjusted = 0.82; 95% CI: 0.69 to 0.97; P = .03). Grip strength was also associated with glycohemoglobin A1C among women with diabetes (βadjusted = –0.26, 95% CI: –0.39 to –0.12; P = .001), which suggests that grip strength is associated with diabetes severity among women.

Conclusions:

For both men and women, grip strength is associated with type 2 diabetes presence, and among women, grip strength is associated with severity of type 2 diabetes.

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Paul D. Loprinzi and Jeremy P. Loenneke

Objective:

Leukocyte telomere length (LTL) shortening is characteristic of aging and is associated with morbidity and mortality, independent of age. Research demonstrates that lower extremity muscular strength is associated with mobility, morbidity and mortality; however, no study, to our knowledge, had examined the association between lower extremity muscular strength and LTL, which was the purpose of this brief study.

Methods:

Data from the 1999–2002 NHANES was used (N = 2410; 50–85 years). Peak isokinetic knee extensor strength (IKES) was objectively measured with LTL assessed from a blood sample.

Results:

After adjustments, for every 50 N increase in IKES, participants had a 9% reduced odds (P = .04) of being in the 1st (vs. 4th) LTL quartile.

Discussion:

Lower extremity muscular strength is associated with LTL, suggesting a possible mechanism through which lower extremity muscular strength may be associated with morbidity and mortality.

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Scott J. Dankel, Jeremy P. Loenneke and Paul D. Loprinzi

Background: Skeletal muscle strength and engagement in muscle-strengthening activities are each inversely associated with all-cause mortality; however, less is known on their relationship with cancer-specific mortality. Methods: Data from the 1999–2002 National Health and Nutrition Examination Survey were used assessing 2773 individuals aged 50 years or older. Individuals being dichotomized at the 75th percentile for knee extensor strength, and engagement in muscle-strengthening activities was acquired through self-report with ≥2 sessions per week were classified as meeting guidelines. Results: With respect to cancer-specific mortality, individuals in the upper quartile for muscle strength were at a 50% reduced risk (hazard ratio = 0.50; 95% confidence interval, 0.29–0.85; P = .01) and those meeting muscle-strengthening activities were at a nonsignificant 8% reduced risk (hazard ratio = 0.92; 95% confidence interval, 0.45–1.86, P = .81) of cancer-specific mortality after adjusting for covariates. Conclusions: Clinicians should routinely assess lower extremity strength and promote engagement in muscle-strengthening activities aimed at increasing muscle strength.

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Takashi Abe, Jeremy P. Loenneke, Robert S. Thiebaud and Mark Loftin

Context: Studies developed the frail elderly handgrip strength (HGS) diagnostic criteria using multiple types of handgrip dynamometers. If different handgrip dynamometers report different values, then this would have the potential to misclassify people into the wrong diagnostic category. Objective: To examine the characteristics of HGS measured by 2 standard handgrip dynamometers and to investigate the influence of hand size on HGS. Setting: University research laboratory. Participants: A total of 87 young and middle-aged adults between the ages of 20 and 60 years participated in this study. Main Outcome Measures: Standard methods of HGS measurements were used for hydraulic and Smedley spring-type dynamometers, although the participants were instructed to maintain an upright standing position in both tests. Results: Test–retest reliability of hydraulic and Smedley dynamometers provided comparable results to that observed with previous studies. However, the difference in HGS between the 2 dynamometers (Hydraulic–Smedley difference) was positively associated (r = .670, P < .001) with the mean of the 2 dynamometers. The participants who had relatively low HGS (at least <35 kg) produced similar HGS values when the 2 dynamometers were compared, whereas persons who had relatively higher HGS (at least >45 kg) produced greater strength values with the hydraulic compared with the Smedley. The hand and palm lengths were weakly correlated (r = .349 and r = .358, respectively, both Ps < .001) with the difference in HGS between the 2 dynamometers. Conclusions: Test–retest reliability of hydraulic and Smedley dynamometers provides comparable results to previous studies. However, the difference in HGS between the 2 dynamometers was positively associated with the mean of the 2 dynamometers. This Hydraulic–Smedley difference would not affect persons who have relatively low HGS (at least <35 kg), while when HGS is relatively high, the comparison between dynamometers should be done with caution.

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Lindy M. Rossow, David H. Fukuda, Christopher A. Fahs, Jeremy P. Loenneke and Jeffrey R. Stout

Bodybuilding is a sport in which competitors are judged on muscular appearance. This case study tracked a drug-free male bodybuilder (age 26–27 y) for the 6 mo before and after a competition.

Purpose:

The aim of this study was to provide the most comprehensive physiological profile of bodybuilding competition preparation and recovery ever compiled.

Methods:

Cardiovascular parameters, body composition, strength, aerobic capacity, critical power, mood state, resting energy expenditure, and hormonal and other blood parameters were evaluated.

Results:

Heart rate decreased from 53 to 27 beats/min during preparation and increased to 46 beats/min within 1 mo after competition. Brachial blood pressure dropped from 132/69 to 104/56 mmHg during preparation and returned to 116/64 mmHg at 6 mo after competition. Percent body fat declined from 14.8% to 4.5% during preparation and returned to 14.6% during recovery. Strength decreased during preparation and did not fully recover during 6 months of recovery. Testosterone declined from 9.22 to 2.27 ng/mL during preparation and returned back to the baseline level, 9.91 ng/mL, after competition. Total mood disturbance increased from 6 to 43 units during preparation and recovered to 4 units 6 mo after competition.

Conclusions:

This case study provides a thorough documentation of the physiological changes that occurred during natural bodybuilding competition and recovery.

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Robert S. Thiebaud, Takashi Abe, Jeremy P. Loenneke, Tyler Garcia, Yohan Shirazi and Ross McArthur

Context: Blood flow restriction (BFR) increases muscle size and strength when combined with low loads, but various methods are used to produce this stimulus. It is unclear how using elastic knee wraps can impact acute muscular responses compared with using nylon cuffs, where the pressure can be standardized. Objective: Investigate how elastic knee wraps compare with nylon cuffs and high-load (HL)/low-load (LL) resistance exercise. Design: A randomized cross-over experimental design using 6 conditions combined with unilateral knee extension. Setting: Human Performance Laboratory. Participants: A total of 9 healthy participants (males = 7 and females = 2) and had an average age of 22 (4) years. Intervention: LL (30% of 1-repetition maximum [1-RM]), HL (70% 1-RM), BFR at 40% of arterial occlusion pressure (BFR-LOW), BFR at 80% of arterial occlusion pressure (BFR-HIGH), elastic knee wraps stretched by 2 in (PRACTICAL-LOW), and elastic knee wraps stretched to a new length equivalent to 85% of thigh circumference (PRACTICAL-HIGH). BFR and practical conditions used 30% 1-RM. Main Outcome Measures: Muscle thickness, maximum voluntary isometric contraction, and electromyography amplitude. Bayesian statistics evaluated differences in changes between conditions using the Bayes factor (BF10), and median and 95% credible intervals were reported from the posterior distribution. Results: Total repetitions completed were greater for BFR-LOW versus PRACTICAL-HIGH (BF10 = 3.2, 48.6 vs 44 repetitions) and greater for PRACTICAL-LOW versus BFR-HIGH (BF10 = 717, 51.8 vs 36.3 repetitions). Greater decreases in changes in maximum voluntary isometric contraction were found in PRACTICAL-HIGH versus HL (BF10 = 1035, ∼103 N) and LL (BF10 = 45, ∼66 N). No differences in changes in muscle thickness were found between LL versus PRACTICAL-LOW/PRACTICAL-HIGH conditions (BF10 = 0.32). Greater changes in electromyography amplitude were also found for BFR-LOW versus PRACTICAL-HIGH condition (BF10 = 6.13, ∼12%), but no differences were noted between the other BFR conditions. Conclusions: Overall, elastic knee wraps produce a more fatiguing stimulus than LL or HL conditions and might be used as an alternative to pneumatic cuffs that are traditionally used for BFR exercise.

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Zachary W. Bell, Scott J. Dankel, Robert W. Spitz, Raksha N. Chatakondi, Takashi Abe and Jeremy P. Loenneke

Context: The perceived tightness scale is suggested to be an effective method for setting subocclusive pressures with practical blood flow restriction. However, the reliability of this scale is unknown and is important as the reliability will ultimately dictate the usefulness of this method. Objective: To determine the reliability of the perceived tightness scale and investigate if the reliability differs by sex. Design: Within-participant, repeated-measures. Setting: University laboratory. Participants: Twenty-four participants (12 men and 12 women) were tested over 3 days. Main Outcome Measures: Arterial occlusion pressure (AOP) and the pressure at which the participants rated a 7 out of 10 on the perceived tightness scale in the upper arm and upper leg. Results: The percentage coefficient of variation for the measurement was approximately 12%, with no effect of sex in the upper (median δ [95% credible interval]: 0.016 [−0.741, 0.752]) or lower body (median δ [95% credible interval]: 0.266 [−0.396, 0.999]). This would produce an overestimation/underestimation of ∼25% from the mean perceived pressure in the upper body and ∼20% in the lower body. Participants rated pressures above their AOP for the upper body and below for the lower body. At the group level, there were differences in participants’ ratings for their relative AOP (7 out of 10) between day 1 and days 2 and 3 for the lower body, but no differences between sexes for the upper or lower body. Conclusions: The use of the perceived tightness scale does not provide reliable estimates of relative pressures over multiple visits. This method resulted in a wide range of relative AOPs within the same individual across days. This may preclude the use of this scale to set the pressure for those implementing practical blood flow restriction in the laboratory, gym, or clinic.