POWER & THE AGING


POWER & RESISTANCE TRAINING – AGING


CONCURRENT TRAINING IN OLDER MEN: HIIT COMBINED WITH POWER TRAINING OR TRADITIONAL STRENGTH TRAINING


Diana Carolina Müller 1Mikel Izquierdo 2 3Francesco Pinto Boeno 1Per Aagaard 4Juliana Lopes Teodoro 1Rafael Grazioli 1Regis Radaelli 1Henrique Bayer 1Rodrigo Neske 1Ronei Silveira Pinto 1Eduardo Lusa Cadore
METHOD
– 16-weeks with two CT models in older men: high-intensity interval training (HIIT) combined with either Traditional Strength Training TST or Power Training PT
35 older men (65.8 ± 3.9 yrs)
Group 1: CTS: TST + HIIT (n = 18) resistance training at intensities ranging from 65 to 80% of 1 RM at slow controlled speed
Group 2: CTP: PT + HIIT (n = 17) trained at intensities ranging from 40 to 60% of 1 RM at maximal intentional speed
– Lower body one-repetition maximum (1 RM), isometric rate of force development (RFD), countermovement jump (CMJ) muscle power output, quadriceps femoris muscles thickness (QF MT), and peak oxygen uptake (VO2peak) were assessed before training and after 8 and 16 weeks of CT
RESULTS
– Groups improved similarly in all primary outcomes, with mean increases ranging: 1 RM (39.4 to 75.8%); RFD (9.9 to 64.8%); CMJ muscle power (1.8 to 5.2%)
– Significant increases in all secondary outcomes (QF MT, specific tension and VO2peak) with no differences between groups
– CT models were effective for improving maximal and explosive force (1 RM, RFD, and CMJ power), QF MT, and VO2peak.
Despite that using lower loading intensities, PT induced similar adaptations to those of TST

 


HIGH SPEED RESISTANCE TRAINING ↑ FUNCTIONAL CAPACITY & MUSCLE PERFORMANCE IN WOMEN >60


Ramírez-Campillo R1, Izquierdo M
OBJECTIVE
– 12 wks high-speed resistance training (RT) vs. low-speed RT:
(1) muscle strength: Leg Press 1 RM and bench-press 1 RM
(2) dominant (HGd) and non-dominant maximum isometric handgrip
(3) power – counter-movement jump (CMJ)
(4) ball throwing (BT)
(5) 10-m walking sprint (S10)
(6) functional performance: 8-foot up-and-go test (UG)
(7) sit-to-stand test (STS)
(8) perceived quality of life in older women
METHODS
– 45 older women were divided into:

(1) high-speed RT group [EG, n=15, age=66.3±3.7y]
(2) low-speed RT group [SG, n=15, age=68.7±6.4y]
(3) control group [CG, n=15, age=66.7±4.9y].
– EG and SG did a 12-week RT program: 3 sets x 8 reps at 40-75% of 1RM plus CMJ and BT
– EG did <1 sec. concentric muscle actions
– SG did 3 sec. concentric muscle actions

RESULTS
(1) Both RT groups showed small to large improvements in the dependent variables
(2) EG vs. SG for changes in Ball Throw (20% vs 11%), 10 meter walking sprint (14% vs 9%) and Up and Go (18% vs 10%)
(3) No significant changes were observed for the CG


ECCENTRIC & STRETCH SHORTENING CYCLE (SSC) EXERCISES IN MALES 60-70


Váczi MHortobágyi T 
AIM
– Test whether training of the quadriceps with low rate ECC and high rate ECC contractions in the form of stretch-shortening cycles (SSCs) but at equal total mechanical work would produce rate-specific adaptations in healthy males age 60-70
RESULTS
(1) Both training programs produced similar improvements in maximal voluntary isometric (6%) and ECC torque (23%) and stretch-shortening cycle function (reduced contraction duration [24%] and enhanced elastic energy storage [12%])
(2) The rate of torque development increased 30% only after SSC exercise
(3) Resting testosterone and cortisol levels were unchanged but after each program acute exercise-induced cortisol levels were 12-15% lower
(4) Both programs increased quadriceps size at 2.5%
CONCLUSIONS
(1) Both ECC and SSC exercise training produces favorable adaptations in healthy old males’ quadriceps muscle
(2) Although rate of muscle tension during SSC vs. ECC was 4x greater, total mechanical work seems to regulate  hypertrophic, hormonal, and most mechanical adaptations
(3) However, SSC exercise was uniquely effective in improving a key deficiency of aging muscle, i.e., its ability to produce force rapidly


EXERCISES INCLUDING POWER TRAINING ENHANCE OUTCOMES IN >90


Eduardo L. Cadore, Mikel Izquierdo
METHOD
– 24 elderly (91.9 ± 4.1 yrs)
– 2x/wk, 12-wk power resistance training (8–10 reps, 40–60 % 1RM) combined with balance and gait retraining

POWER TRAINING IMPROVES OVER 90 GROUP
(1) Significantly improved:
– Time-Up-and-Go TUG with single and dual tasks
– Rise from a chair
– Balance performance
– Reduced incidence of falls

(2) Enhanced muscle power and strength
(3) Significant increases in total and high-density muscle cross-sectional area


 EFFECTS OF HIGH & LOW VELOCITY RESISTANCE TRAINING ON MUSCLE


Dennis R. Claflin,  John A. Faulkner, and James A. Ashton-Miller et al
METHOD
– progressive resistance training (PRT)
(1) 63 subjects organized into 4 groups:
– young (20–30 yr) men and women
– older (65–80 yr) men and women

(2) In each group, half the subjects underwent a traditional PRT protocol that involved shortening contractions at low velocities against high loads
(3) The half performed a modified PRT protocol that involved contractions at 3.5x higher velocity against reduced loads

RESULTS
(1) Both types of PRT increased cross-sectional area, force, and power of type 2 fibers by 8–12%, independent of sex or age of subject
(2) Contrary to our hypothesis, the velocity at which the PRT was performed did not affect the fiber-level outcomes substantially
CONCLUSIONS
– Compared with low-velocity PRT, resistance training performed at velocities up to 3.5x higher against reduced loads is equally effective for eliciting an adaptive response in type 2 fibers from human skeletal muscle


POWER & NEUROMUSCULAR FACTORS – AGING


AGE-RELATED CHANGES IN THE RATE OF MUSCLE ACTIVATION AND RAPID FORCE CHARACTERISTICS

PURPOSE & METHODS
– Investigate the effects of aging on the rate of muscle activation and rapid force characteristics of the plantar flexors
– Plantar flexion peak force (PF), absolute (peak, 50, and 100–200 ms), and relative (10 %, 30 %, and 50 %) rate of force development (RFD), the rapid to maximal force ratio (RFD/PF), and the rate of electromyography rise (RER) were examined during an isometric maximal voluntary contraction (MVC)
(A) Young (age = 22 ± 2 years)
(B) Middle-aged (43 ± 2 years)
(C) Old (69 ± 5 years) men
RESULTS
– The old men exhibited lower PF (30.7 % and 27.6 % lower, respectively) and absolute (24.4–55.1 %) and relative (16.4–28.9 %) RFD values compared to the young and middle-aged men
– RER values were similar between the young and old men
– However, RER values were greater for the middle-aged men when compared to the young and old men for the soleus and the old men for the medial gastrocnemius
– Likewise, RFD/PF ratios were similar between young and old men
– However, these ratios were greater for the middle-aged men at early, but not later, time intervals
– The lower PF and absolute and relative RFD values for the old men may contribute to the increased functional limitations often observed in older adults
– Interestingly, higher rates of muscle activation and greater early RFD/PF ratios in middle-aged men may be a reflection of physiological alterations in the neuromuscular system occurring in the fifth decade.

THE NERVOUS SYSTEM – SARCOPENIA & MUSCLE ATROPHY


Aagaard P1, Suetta C, Caserotti P, Magnusson SP, Kjaer M.
(1) Aging is characterized by:
– loss of spinal motor neurons (MNs)
– reduced insulin-like growth factor I signaling
– elevated amounts of circulating cytokines
– increased cell oxidative stress
(2) The loss of spinal MNs is paralleled by a reduction in muscle fiber number and size (sarcopenia), resulting in impaired mechanical muscle performance
(3) Maximum muscle strength, power, and rate of force development are decreased with aging, even in highly trained master athletes
(4) Impairment in muscle mechanical function is accompanied and partly caused by an age-related loss in neuromuscular function that comprise changes in maximal MN firing frequency, agonist muscle activation, antagonist muscle coactivation, force steadiness, and spinal inhibitory circuitry
(5) Strength training appears to elicit effective countermeasures in elderly individuals even at a very old age (>80 years) by evoking muscle hypertrophy along with substantial changes in neuromuscular function, respectively


IMPAIRED VOLUNTARY NEUROMUSCULAR ACTIVATION LIMITS MUSCLE POWER IN MOBILITY LIMITED OLDER ADULTS


David J. Clark, Carolynn Patten, […], and Roger A. Fielding
TEST GROUPS
– MH (aged 40–55 years), OH (aged 70–85 years), and OML (aged 70–85 years)
– We determined the effect of movement velocity on torque and power production in older healthy adults (OH) and older mobility–limited (OML) adults relative to middle-aged healthy adults (MH)
RESULTS
(1) Neuromuscular activation was similar b/n middle-aged and older healthy groups
(2) Differences in torque and power were explained predominantly by muscle size
(3) The older mobility–limited group demonstrated marked impairment of torque, power, and agonist muscle activation, with the greatest deficits occurring at the fastest movement velocities
(4) Agonist muscle activation was found to be strongly associated with torque output
CONCLUSIONS
(1) Similar neuromuscular activation between the middle-aged and older healthy groups indicates that impaired voluntary activation is not an obligatory consequence of aging
(2) However, the finding that the mobility-limited group exhibited impaired activation of the agonist quadriceps and concomitant deficits in torque and power output suggests that neuromuscular activation deficits may contribute to compromised mobility function in older adult


ELITE MALE ATHLETES: AGE-RELATED CHANGES IN PERFORMANCE & MUSCLE


Faulkner JA1, Davis CS, Mendias CL, Brooks SV.
OBJECTIVE
– Address the degree to which the attainment of the status as an elite athlete in different sports ameliorates the known age-related losses in skeletal muscle structure and function
MAIN OUTCOME MEASUREMENTS
– Strength, power, VO2max, and performance
RESULTS
1. For elite athletes in all sports, as for the general population, age-related muscle atrophy begins at about 50 years of age
2. Despite the loss of muscle mass, elite athletes who maintain an active lifestyle age gracefully with few health problems
3. Conversely, those who lapse into inactivity regress toward general population norms for fitness, weight control, and health problems
4. Elite athletes in the dual and team sports have careers that rarely extend into their 30s
CONCLUSIONS
– Lifelong physical activity does not appear to have any impact on the loss in fiber number
– The loss of fibers can be buffered to some degree by hypertrophy of fibers that remain
– It is surprising that the performance of elite athletes in all sports appears to be impaired before the onset of the fiber loss
– Even with major losses in physical capacity and muscle mass, the performance of elite and masters athletes is remarkable


POWER & BALANCE – AGING


DOES A RELATIONSHIP EXIST BETWEEN LOWER BODY POWER AND BALANCE SCORES AMONG OLDER ADULTS?


METHODS
– center of pressure (CoP) and limits of stability (LoS)
– A one-shot case study design (n = 13) was selected for the investigation
– All participants were assessed stability scores via computerized posturography to determine CoP and LoS balance scores
– Participants stood on a perturbed surface with their eyes open and closed
– An experimental stair ramp with a switch mat timing device was used to determine lower body power scores in watts
RESULTS
– There was a strong correlation between the posterior (LoS) plane and relative peak power
– An intraclass R revealed a strong correlation among the three trials performed on the stair ramp
CONCLUSION
– Muscle power output and LoS scores have moderate to strong correlations with balance scores in older adults


POWER & OXIDATIVE STRESS – AGING


OXIDATIVE STRESS RESPONSES TO MAXIMAL TEST FOLLOWING EXPLOSIVE TYPE RESISTANCE TRAINING IN 70-75 YR OLDS


INTRODUCTION
– Low frequency, moderate intensity, explosive-type resistance training (EMRT) is highly beneficial in elderly subjects
– Muscle strength and power, with a systemic adaptive response of anti-oxidant and stress-induced markers
AIM/METHODS
– Evaluate the impact of EMRT on oxidative stress induced in people (70-75 yrs) by a single bout of acute, intense exercise
(1) 16 subjects assigned to not exercising group (n=8) or trained group performing EMRT protocol for 12-weeks (n=8)
(2) submitted to a graded maximal exercise stress test (GXT) at baseline and after the 12-weeks of EMRT protocol
CONCLUSION
– EMRT induced a cellular adaptation allowing healthy elderly trained subjects to cope with the oxidative stress induced by an acute exercise


POWER & TORQUE DEPRESSION – AGING


SHORTENING-INDUCED TORQUE DEPRESSION – IMPLICATIONS FOR AGE-RELATED POWER LOSS FOR >70


Power GA1, Vandervoort AA5. et al
METHOD
– Maximal voluntary isometric dorsiflexion contractions (MVC; 10s) in 8 young (25.5±3.7yrs) and 9 old (76.1±5.4yrs) men were performed and then again following an active shortening of 40° joint excursion (40°PF-0°PF) at angular velocities of 15°/s and 120°/s
RESULTS
(1) Old were 18% weaker than young for MVC, and ~40% less powerful for 15°/s and 120°/s of shortening
(2) Old produced 37% and 21% less work for 15°/s and 120°/s than young, respectively.
(3) Old experienced 60% and 70% greater shortening induced TD than young for 15°/s and 120°/s, respectively
(4) Significant relationship b/n shortening-induced TD and instantaneous power only at fast angular velocity for both old and young
(5) The older men experienced greater shortening induced TD than young while maintaining similar levels of voluntary activation
CONCLUSION
– This previously unaccounted for history-dependent property of muscle may provide insight into power loss in old age


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