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ABSTRACT: Morris, CE, Arnett, SW, and Winchester, LJ. Comparing physical fitness in career vs. volunteer firefighters. J Strength Cond Res 36(5): 1304-1309, 2022-The purpose of this study was to assess the potential similarities and differences in health and physical fitness profiles between career firefighters (CFF) and volunteer firefighters (VFF). The research protocol consisted of a health and physical fitness assessment, testing the 5 components of health-related fitness using previously published and accepted protocols. The subject population consisted of a total of 138 firefighters, including 119 CFF and 19 VFF. Statistical significance was defined as a p level less than 0.05. An independent t test showed evidence of CFF having a significantly higher value/score for the following variables: height (p = 0.034), V̇o2max (p = 0.006), push-ups completed (p = 0.024), and plank time (p < 0.001). Volunteer firefighters had a significantly higher value for the following variables: fat mass (p = 0.002), body fat percentage (p < 0.001), and absolute grip strength (p = 0.029). There were no significant differences between groups for the following variables: age (p = 0.299), body mass (p = 0.166), fat-free mass (p = 0.281), body mass index (p = 0.057), flexibility (p = 0.106), or relative grip strength (p = 0.887). With regard to physical fitness testing, the VFF had a significantly worse fitness profile across a number of variables than the CFF. Practical applications: Despite the financial and commitment status of volunteer firefighting departments, their members perform an equally dangerous and important job as do firefighters of professional/career firefighting departments, and more attention should be directed toward developing the fitness and performance of these firefighters.

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There are limited data comparing the efficacy of resistance loads within the hypertrophy range for promoting muscular growth, particularly when similar training volumes are utilized. The purpose of this study was to determine if two similar volume-loads, utilizing different intensities, would produce dissimilar muscular damage and inflammation. Eleven resistance-trained, college-aged males participated in this study. After testing 1RM barbell squats, participants completed two similar volume-load barbell squat sessions at two different resistance loads (67% and 85% of 1RM) on two separate visits. Venous blood samples were collected at baseline and one hour after completion of each exercise session. Plasma was isolated and analyzed for myoglobin and C-reactive protein (CRP) expression via ELISA. Plasma myoglobin expression was significantly elevated above baseline (BASE) values only after the 85% of 1RM (HHL) session (p =0.031), though the 67% (LHL) trial (p = 0.054; η2 = 0.647) was approaching significance (BASE: 1.42±.12 ng/mL; LHL: 4.65±1.13 ng/mL; HHL: 5.00±1.01 ng/mL). No changes in plasma CRP were observed. Despite attempts to equate volumes between resistances, mean total volume-load was significantly higher during the 67% of 1RM trial than during the 85% trial. Resistance loads at 85% of 1RM inflict significantly increased muscle damage over baseline values, even when significantly less total volume was lifted during the 85% trial. Individuals looking to maximize strength and hypertrophy during general training or during rehabilitation may benefit from these findings when determining the appropriate training load.

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Cardiorespiratory endurance is an important element of aerobic fitness, particularly in weight management and reducing risk for cardiovascular disease. While there are numerous options for aerobic exercise, rope jumping is often overlooked. In addition to regular exercise and a healthy diet, the American Heart Association strongly recommends rope jumping. The first purpose of this study was to determine the steady state metabolic cost of repetitive jumping on the Digi-Jump machine to evaluate whether exercise on this device is more or less strenuous than similar exercise with a jump rope, as demonstrated in previous literature. A second purpose was to determine the relative intensity of exercise on the Digi-Jump by comparing to VO2max as measured on a treadmill. Twenty-seven participants completed two trials, one jumping trial at a rate of 120 jumps per minute with the jumping height set at 0.5 inch for 5-min on the Digi-Jump, and one graded exercise test using the Bruce protocol. Oxygen uptake (VO2), heart rate (HR), respiratory exchange ratio (RER), and rating of perceived exertion (RPE) were measured each minute during each trial. Results of this study indicated that steady state VO2 during the 5-min jump test was reached at the 3rd min. Steady state variables during the jumping trial expressed as percentage of max were as follows: VO2 was 57.1% of VO2max; HR was 80.9% of HRmax; RER was 86%of RERmax; and RPE was 75.2% of RPEmax. These data indicate that repetitive jumping is a strenuous activity and similar in intensity to jumping rope, even if the trial is done on the Digi-Jump machine with free-swinging arms and without a jump rope.

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Cardiovascular (CV) and resistance training (RT) can moderate negative effects of aging, disease, and inactivity. Post-exercise hypotension (PEH) has been used as a non-pharmacological means to control and reduce BP. Few have evaluated PEH response following a bout of exercise combining CV and RT, whether or not there is an order effect, or if PEH continues when activities of daily living (ADLs) are resumed. Participants (N = 10) completed a non-exercise control, a graded exercise test (GXT), and two concurrent sessions (CVRT and RTCV). Each session was followed by a 60-minute laboratory and 3-hour ADLs PEH assessment, respectively. Two-way and Welch-one-way repeated measures ANOVAs were used to determine differences between among conditions in PEH. There was a significant interaction between BP and condition following the 60-minute laboratory measure (p = .030, ηp 2 = .166) and the ADLs BP assessments (p = .008, ηp 2 = .993), respectively. PEH occurred following concurrent exercise conditions at minute 45 for RTCV (118 ± 8, p = .041; 95% CI [0.223, 17.443]) and minutes 50 (117 ± 9; p = .036 95% CI [0.441, 21.097]) and 55 (118 + 8; p < .001; 95% CI [5.884, 14.731]) following CVRT. BP was elevated during ADLs following the control session compared to the GXT, RTCV, and CVRT. Regardless of the order, concurrent exercise is effective in potentiating PEH. Elevation in BP associated with ADLs can be mitigated if exercise is performed previously.

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Background. This study aimed to evaluate the physiological strain index (PSI) along with specific immune system markers in response to a simulated firefighting occupation workload. Methods. Ten healthy male adults completed a 6-min simulated fire stair climb (SFSC) at 60 steps/min. The protocol consisted of four conditions, some including wearing a 34.04-kg vest to simulate personal protective equipment (PPE) and/or inclusion of a color-word interference test (CWIT) as a distracting mechanism. The PSI was evaluated by continuously monitoring the heart rate and core temperature. Salivary cortisol (CORT) was measured at baseline, mid SFSC and post SFSC. C-reactive protein (CRP) was evaluated at baseline and 1 h post SFSC. Results. Repeated-measures analysis of variance showed a significantly different PSI across conditions (p = 0.001). A significantly elevated PSI was exhibited during all 6 min of SFSC for both PPE and PPE + CWIT conditions. Neither CORT (p = 0.116) nor CRP (p = 0.700) was significantly different across conditions or from baseline. Conclusion. These findings suggest that firefighters are potentially at a substantial degree of physiological stress from exercise and the weight of gear alone. Further work should be conducted to further evaluate the usefulness of the PSI as a means to monitor firefighters during fire suppression.

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BACKGROUND: Knee Savers® (KS) are an ergonomic aid purported to lessen the risk of injuries linked to deep squats. While widely used in sports such as baseball and softball, KS have not been tested to determine their effect upon lower extremity kinematics in any population. PURPOSE: The purpose of the study was to determine if KS influenced the lower extremity kinematics when females with previous anterior cruciate ligament (ACL)-reconstruction and healthy participants completed an end-range squat. STUDY DESIGN: A repeated measures, counter-balanced laboratory study design was used. METHODS: Twenty female participants (mean (SD) - age: 21.65 (2.06) yrs, height: 175.26 (9.29) cm, weight: 64.66 (7.72) kg) with a history of ACL-repair (n=10) or non-injury (n=10) completed this study. Participants completed a standardized trial of three deep squats with and without KS. Movement was analyzed using 2D video analysis methods increasingly available in clinical environments. RESULTS: During the ascending phases of a squatting motion, there was significantly greater medial (p = .009) and lateral (p = .005) motion of the patella in the frontal plane for non-injured participants, when compared to the ACL-repaired group. No significant differences were found in sagittal plane lower extremity kinematics when squatting with and without KS. Ascending angular velocity was slower in ACL-repaired than non-injured females (p = .008) and slower with the KS than without KS for non-injured females (p = .007). CONCLUSIONS: When squatting with and without KS, the non-injured group experienced more frontal plane motion at the knee, compared to the ACL-repaired group. However, while KS are purported to influence lower extremity joint positions during the bottom phase of a deep squat, the data from the current study did not support this claim. Additionally, KS appear to slow ascending velocity for those without a history of ACL-repair. These findings may have clinically meaningful implications for athletes who use KS during sport activities. LEVEL OF EVIDENCE: Level 2.

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One potential ACL injury situation is due to contact with another person or object during the flight phase, thereby causing the person to land improperly. Conversely, athletes often have flight-phase collisions but do land safely. Therefore, to better understand ACL injury causation and methods by which people typically land safely, the purpose of this study was to determine the effects of an in-flight perturbation on the lower extremity biomechanics displayed by females during typical drop landings. Seventeen collegiate female recreational athletes performed baseline landings, followed by either unexpected laterally-directed perturbation or sham (nonperturbation) drop landings. We compared baseline and perturbation trials using paired-samples t tests (P < .05) and 95% confidence intervals for lower-extremity joint kinematics and kinetics and GRF. The results demonstrated that perturbation landings compared with baseline landings exhibited more extended joint positions of the lower extremity at initial contact; and, during landing, greater magnitudes for knee abduction and hip adduction displacements; peak magnitudes of vertical and medial GRF; and maximum moments of ankle extensors, knee extensors, and adductor and hip adductors. We conclude that a lateral in-flight perturbation leads to abnormal GRF and angular motions and joint moments of the lower extremity.

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The objective of the study was to determine if prophylactic ankle bracing worn by females during landings produces abnormal lower extremity mechanics. Angular kinematic and ground reaction force (GRF) data were obtained for 16 athletically experienced females who performed brace and no-brace drop landings. The brace condition displayed reduced in/external rotation and flexion displacements about the ankle and knee joints and increased vertical and mediolateral GRF peak magnitudes and rate of vertical GRF application (paired t test, P < .05). The ankle and knee joints landed in a less plantar flexed and more flexed position, respectively. No significant ab/adduction outcomes may have occurred due to interparticipant variability and/or a lack of brace restriction. Conclusion: During typical landings, this lace-up brace increases vertical GRF, decreases ankle and knee joint displacements of flexion and int/external rotation, but minimally affects ab/adduction displacements.

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Studies have shown significant changes in lymphocytes during continuous exercise, but little has been shown on the effect of repeated high intensity bouts. This study was designed to examine the effect of repeated intermittent bouts on lymphocyte subset cell count, apoptosis, and migration. A series of 6 Wingate anaerobic cycle tests were performed by participants (N = 8) with blood samples attained before, immediately following, and after a designated recovery period (excess postexercise oxygen consumption (EPOC)) to observe lymphocyte changes. Lymphocyte subsets (CD4+, CD4/CD45RA+, CD8+, CD8+/CD45RA+, CD19+) were assessed for apoptosis (annexin V+) and cellular migration (CX(3)CR1). Our results indicate that the CD8+ and CD8+/CD45RA+ subsets were significantly influenced by the repetitive Wingate cycling protocol such that cell counts increased with exercise, and then decreased at EPOC termination (p = 0.016). The observed postexercise decrease in CD8+ and CD8+/CD45RA+ cells was accompanied by a significant change in the CX(3)CR1 cell migration receptor (p = 0.019), but not apoptosis (p = 0.87). This indicates that with repetitive high-intensity cycling, the response in CD8+ cells following the bout is likely due to cell migration rather than cell death.

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The purpose of this study was to determine whether a relationship exists between 1-repetition maximum (1RM) performed on hammer strength (HS) machines compared to free weights (FWs) and also to develop regression equations that can accurately predict 1RM when switching from exercise modality to another. Thirty-one trained male subjects performed 1-RM lifts (1RM's) on 3 HS externally loaded machines and 3 comparable FW exercises. Subjects performed 2 1RM tests during each laboratory session, with at least 48-72 hours of recovery between each. One repetition maximum data were used to (a) determine the relationship between 1RM performed on HS vs. FW and (b) to develop regression equations that can accurately predict 1RM's when switching from 1 exercise modality to another. Statistics revealed significant differences (p < 0.05) between 1RM's performed on the HS equipment as compared to its corresponding (FW) exercise. For all exercises, 1RM's were significantly greater on the HS equipment. Regression equations were developed for all exercises, except when predicting the HS shoulder press and the HS preacher curls from their free weight counterparts, where no variables existed that could significantly predict their respective 1RM's. As 1 RMs were significantly greater when using the HS equipment compared to when using FWs, those transitioning from HS exercise to FW exercise should exercise caution.

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BACKGROUND: older adults can be limited in their performance of daily tasks due to an inadequate aerobic capacity. Aerobic capacity below minimum physiological thresholds required to maintain independence leaves older adults with little, or no, aerobic reserve. OBJECTIVE: the aim of this study was to measure functional performance and aerobic reserve in older adults during the serial performance of daily tasks. SUBJECTS: twenty-nine (n = 29) men and women (n = 23 females) 70-92 years of age participated in this study. METHODS: performance based physical function was assessed using the Continuous-Scale Physical Functional Performance test (CS-PFP). A Cosmed K4b(2) portable metabolic system was used to measure VO(2PEAK) and oxygen uptake during the serial performance of a battery of daily tasks (VO(2PFP)). Aerobic reserve was calculated as the difference between VO(2PEAK) and VO(2PFP). RESULTS: the correlation coefficient between aerobic reserve and functional performance was r = 0.50(P = 0.006). Participants utilized 32.2 +/- 8.1%, 42.7 +/- 10.8%, and 50.3 +/- 12.3% of VO(2PEAK) for the low, moderate, and high workloads of the CS-PFP, respectively. CONCLUSIONS: light housework and carrying groceries require 40 to 50% of peak oxygen consumption. This information can be used by clinicians and health professionals working with older adults as a guide to how much aerobic fitness is needed to perform ADLs and maintain independence. These can then be used as guides for assessment and for setting training goals in older adults.

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