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Weston AR, Doar G, Dibble LE, Loyd BJ. Vestibular Decompensation Following COVID-19 Infection in a Person With Compensated Unilateral Vestibular Loss: A Rehabilitation Case Study. J Neurol Phys Ther 2024; 48:112-118. [PMID: 38414133 DOI: 10.1097/npt.0000000000000465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
BACKGROUND AND PURPOSE Surgical removal of a vestibular schwannoma (vestibular schwannoma resection; VSR) results in a unilateral vestibular hypofunction with complaints of dizziness and imbalance. Although the anatomic lesion is permanent, recovery of balance and diminution of dizziness occurs through central neurophysiologic compensation. Compensation of the system is maintained through daily activity. Unfortunately, interruption of stimulus, such as decreased activities due to illness, can cause decompensation. Decompensation is described as the return of symptoms consistent with that experienced during the initial insult/injury (eg, dizziness, oscillopsia, balance difficulty). This case study describes a reoccurrence of vestibular dysfunction in a person with a history of VSR following hospitalization and protracted recovery from a COVID-19 infection. It further documents her recovery that may be a result of vestibular rehabilitation. CASE DESCRIPTION A 49-year-old woman (M.W.) with a surgical history of VSR (10 years prior) and a medical history of significant COVID-19 infection, resulting in an intensive care unit stay and prolonged use of supplemental oxygen, presented to physical therapy with persistent dizziness and imbalance. The video head impulse test confirmed unilateral vestibular hypofunction. INTERVENTION M.W. attended biweekly vestibular rehabilitation for 6 weeks and completed daily home exercises. OUTCOMES At discharge, M.W. demonstrated improvements in patient-reported outcomes (Dizziness Handicap Inventory), functional testing (MiniBEST, 2-Minute Walk Test), and gaze stability measures (video head impulse testing, dynamic visual acuity). DISCUSSION Vestibular decompensation preluded by a COVID-19 infection caused a significant decrease in functional mobility. Vestibular rehabilitation targeted at gaze and postural stability effectively reduced symptoms and facilitated recovery to M.W.'s pre-COVID-19 level of function. Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1 available at: http://links.lww.com/JNPT/A458 ).
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Affiliation(s)
- Angela R Weston
- Department of Physical Therapy and Athletic Training (A.R.W., G.D., L.E.D.), The University of Utah, Salt Lake City; Army Baylor University Doctoral Program in Physical Therapy (A.R.W.), U.S. Army Medical Center of Excellence, San Antonio; and School of Physical Therapy and Rehabilitation Sciences & School of Integrative Physiology and Athletic Training (B.J.L.), University of Montana, Missoula
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Weston AR, Lohse KR, Kittelson A, King LA, Carlson-Kuhta P, Dibble LE, Mancini M. Turning speed as a more responsive metric of age-related decline in mobility: A comparative study with gait speed. Clin Biomech (Bristol, Avon) 2024; 113:106196. [PMID: 38354515 PMCID: PMC10955671 DOI: 10.1016/j.clinbiomech.2024.106196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 01/30/2024] [Accepted: 02/03/2024] [Indexed: 02/16/2024]
Abstract
BACKGROUND Navigating your environment requires both straight-line gait as well as turning. Gait speed normative values are well established and utilized in determining a person's functional status, however, it has limitations. This study sought to examine whether turning speed declines with age and how it compared to gait speed age-related decline. METHODS A secondary analysis was performed on 275 community dwelling adults between the ages of 18-88 that performed a timed walking test with an inertial measurement unit on their lumbar spine. Turning speed and walking speed were extracted for each participant. A series of mixed models were compared, and Akaike's Information Criterion was used to determine the best fit model between age and turning speed and age and gait speed. FINDINGS Turning speed and gait speed normative values were reported for each age decade. A linear model with a random intercept of "Condition" was used to assess the relationship between age and turning speed. The results indicated a significant negative relationship between age and turning speed (B = -0.66, p < 0.001). A spline-fit model determined a significant negative relationship between age and gait speed after the age of 65 (B = -0.0097, p = 0.002). The effect of age on gait speed before age 65 was not significant. INTERPRETATION Turning speed significantly declines with age in a linear fashion while gait speed begins to decline after age 65. Turning speed may be more responsive to age than gait speed. More research is needed to determine if the decline in turning speed with age is associated with a decline in function.
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Affiliation(s)
- Angela R Weston
- Army-Baylor University Doctoral Program in Physical Therapy, U.S. Army Medical Center of Excellence, 3630 Stanley Road, San Antonio, TX 78234, United States; Department of Physical Therapy & Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84108, United States.
| | - Keith R Lohse
- Program in Physical Therapy and Department of Neurology, Washington University School of Medicine in Saint Louis, 4444 Forest Park Ave., Suite 1101, Saint Louis, MO 63108, United States.
| | - Andrew Kittelson
- School of Physical Therapy and Rehabilitation Science, University of Montana, 32 Campus Dr., Missoula, MT 59812, United States; School of Integrative Physiology and Athletic Training, University of Montana, 32 Campus Dr., Missoula, MT 59812, United States.
| | - Laurie A King
- Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, United States.
| | - Patty Carlson-Kuhta
- Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, United States.
| | - Leland E Dibble
- Department of Physical Therapy & Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84108, United States.
| | - Martina Mancini
- Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, United States.
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Weston AR, Antonellis P, Fino PC, Hoppes CW, Lester ME, Weightman MM, Dibble LE, King LA. Quantifying Turning Tasks With Wearable Sensors: A Reliability Assessment. Phys Ther 2024; 104:pzad134. [PMID: 37802908 DOI: 10.1093/ptj/pzad134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 07/05/2023] [Accepted: 10/02/2023] [Indexed: 10/08/2023]
Abstract
OBJECTIVE The aim of this study was to establish the test-retest reliability of metrics obtained from wearable inertial sensors that reflect turning performance during tasks designed to imitate various turns in daily activity. METHODS Seventy-one adults who were healthy completed 3 turning tasks: a 1-minute walk along a 6-m walkway, a modified Illinois Agility Test (mIAT), and a complex turning course (CTC). Peak axial turning and rotational velocity (yaw angular velocity) were extracted from wearable inertial sensors on the head, trunk, and lumbar spine. Intraclass correlation coefficients (ICCs) were established to assess the test-retest reliability of average peak turning speed for each task. Lap time was collected for reliability analysis as well. RESULTS Turning speed across all tasks demonstrated good to excellent reliability, with the highest reliability noted for the CTC (45-degree turns: ICC = 0.73-0.81; 90-degree turns: ICC = 0.71-0.83; and 135-degree turns: ICC = 0.72-0.80). The reliability of turning speed during 180-degree turns from the 1-minute walk was consistent across all body segments (ICC = 0.74-0.76). mIAT reliability ranged from fair to excellent (end turns: ICC = 0.52-0.72; mid turns: ICC = 0.50-0.56; and slalom turns: ICC = 0.66-0.84). The CTC average lap time demonstrated good test-retest reliability (ICC = 0.69), and the mIAT average lap time test-retest reliability was excellent (ICC = 0.91). CONCLUSION Turning speed measured by inertial sensors is a reliable outcome across a variety of ecologically valid turning tasks that can be easily tested in a clinical environment. IMPACT Turning performance is a reliable and important measure that should be included in clinical assessments and clinical trials.
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Affiliation(s)
- Angela R Weston
- Department of Physical Therapy & Athletic Training, University of Utah, Salt Lake City, Utah, USA
- Army-Baylor University Doctoral Program in Physical Therapy, Fort Sam Houston, San Antonio, Texas, USA
| | - Prokopios Antonellis
- Department of Neurology, Oregon Health & Science University, Portland, Oregon, USA
| | - Peter C Fino
- Department of Health and Kinesiology, University of Utah, Salt Lake City, Utah, USA
| | - Carrie W Hoppes
- Army-Baylor University Doctoral Program in Physical Therapy, Fort Sam Houston, San Antonio, Texas, USA
| | - Mark E Lester
- Department of Physical Therapy, University of Texas Rio Grande Valley, Harlingen, Texas, USA
| | | | - Leland E Dibble
- Department of Physical Therapy & Athletic Training, University of Utah, Salt Lake City, Utah, USA
| | - Laurie A King
- Department of Neurology, Oregon Health & Science University, Portland, Oregon, USA
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Weston AR, Dibble LE, Fino P, Lisonbee R, Hoppes C, Loyd BJ. Recovery of turning speed in patients after vestibular schwannoma resection. J Vestib Res 2024; 34:145-157. [PMID: 38669501 DOI: 10.3233/ves-230097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
BACKGROUND Individuals after a vestibular schwannoma resection (VSR) experience significant vestibular symptoms that can be provoked with turning. Vestibular rehabilitation assists in recovery of function and symptom relief, however turning response is unknown. OBJECTIVE Examine peak turning speed response to surgery and rehabilitation. METHODS Eight participants with a vestibular schwannoma (PwVS) and five healthy controls (HC) participated in this study. Peak turning speed (PTS) was captured with inertial measurement units (IMU) at the head and/or trunk during turning tasks at a pre-operative, post-operative and post-treatment assessment. Vestibular rehabilitation was provided twice weekly for six weeks. Linear mixed models were used to assess change in PTS across time points. RESULTS PwVS performed slower PTS than HC prior to surgery. PTS was significantly slower post-operatively compared to pre-operative during walking with head turns (B = -61.03, p = 0.004), two-minute walk test (B = -37.33, p = 0.015), 360° turn (B range from 50.05 to -57.4, p < 0.05) and complex turning course (CTC) at the trunk (B = -18.63, p = 0.009). Post-treatment PTS was significantly faster than pre-operative during CTC at the head (B = 18.46, p = 0.014) and trunk (B = 15.99, p = 0.023). CONCLUSION PwVS may have turning deficits prior to surgical resection. PTS was significantly affected post-operatively, however improved with rehabilitation.
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Affiliation(s)
- Angela R Weston
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, UT, USA
- Army-Baylor University Doctoral Program in Physical Therapy, U.S. Army Medical Center of Excellence, San Antonio, TX, USA
| | - Leland E Dibble
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, UT, USA
| | - Peter Fino
- Department of Health and Kinesiology, University of Utah, UT, USA
| | - Rich Lisonbee
- Department of Orthopedics, University of Utah, UT, USA
| | - Carrie Hoppes
- Army-Baylor University Doctoral Program in Physical Therapy, U.S. Army Medical Center of Excellence, San Antonio, TX, USA
| | - Brian J Loyd
- School of Physical Therapy and Rehabilitation Sciences, University of Montana, Missoula, MT, USA
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Weston AR, Dibble LE, Hoppes CW, Loyd BJ. People with multiple sclerosis and unilateral peripheral vestibular loss demonstrate similar alterations in head and trunk turning kinematics compared to healthy controls. Gait Posture 2023; 105:132-138. [PMID: 37562112 DOI: 10.1016/j.gaitpost.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 07/11/2023] [Accepted: 08/03/2023] [Indexed: 08/12/2023]
Abstract
BACKGROUND Individuals with peripheral vestibulopathy are known to have difficulty with volitional head turns. This leads to differences in head and body turning kinematics, compared to those without vestibular dysfunction. Multiple sclerosis (MS), a neuro-inflammatory disease affecting the central nervous system, can cause vestibular dysfunction (dizziness, unsteadiness, gaze instability). However, head and trunk turning kinematics in people with MS (PwMS) have not been assessed. RESEARCH QUESTION Will PwMS, demonstrate head and body kinematics alterations similar to individuals with a peripheral dysfunction compared to vestibular healthy individuals? METHODS Eleven individuals with a recent vestibular schwannoma resection (VSR), fourteen PwMS, and 10 healthy control (HC) participants were fitted with head and trunk worn inertial measurement units (IMUs) and performed walking and turning tasks. Head and trunk peak turning speed and amplitude were extracted. Regression models controlling for gait speed were fit per outcome with post hoc corrections applied to significant models. RESULTS Yaw plane head turn speed and amplitude were significantly less in the VSR group compared to HC. Pitch plane head turn amplitude was significantly smaller in PwMS compared to HC (p = 0.04), however pitch plane speed did not differ between the groups. There was no difference between PwMS and the VSR group in yaw or pitch plane speed and amplitude. Both PwMS and the VSR group turned significantly slower than HC during the 180d body turn as measured at the head and trunk (head speed model p = 0.009 and <0.001; trunk speed model p < 0.001 for both groups) however the MS and VSR groups did not differ from each other. SIGNIFICANCE Turning kinematics while walking in PwMS are altered compared to HC and are similar to individuals with unilateral vestibular hypofunction. Centrally mediated vestibular dysfunction in PwMS may alter movement kinematics and should be considered during examination and treatment.
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Affiliation(s)
- Angela R Weston
- Department of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84108, USA; Army-Baylor University Doctoral Program in Physical Therapy, Fort Sam Houston, TX, 78234 USA.
| | - Leland E Dibble
- Department of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84108, USA.
| | - Carrie W Hoppes
- Army-Baylor University Doctoral Program in Physical Therapy, Fort Sam Houston, TX, 78234 USA.
| | - Brian J Loyd
- School of Physical Therapy and Rehabilitation Sciences, University of Montana, 32 Campus Dr., Missoula, MT 59812, USA.
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Weston AR, Loyd BJ, Taylor C, Hoppes C, Dibble LE. Head and Trunk Kinematics during Activities of Daily Living with and without Mechanical Restriction of Cervical Motion. Sensors (Basel) 2022; 22:3071. [PMID: 35459056 PMCID: PMC9026113 DOI: 10.3390/s22083071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/06/2022] [Accepted: 04/12/2022] [Indexed: 11/16/2022]
Abstract
Alterations in head and trunk kinematics during activities of daily living can be difficult to recognize and quantify with visual observation. Incorporating wearable sensors allows for accurate and measurable assessment of movement. The aim of this study was to determine the ability of wearable sensors and data processing algorithms to discern motion restrictions during activities of daily living. Accelerometer data was collected with wearable sensors from 10 healthy adults (age 39.5 ± 12.47) as they performed daily living simulated tasks: coin pick up (pitch plane task), don/doff jacket (yaw plane task), self-paced community ambulation task [CAT] (pitch and yaw plane task) without and with a rigid cervical collar. Paired t-tests were used to discern differences between non-restricted (no collared) performance and restricted (collared) performance of tasks. Significant differences in head rotational velocity (jacket p = 0.03, CAT-pitch p < 0.001, CAT-yaw p < 0.001), head rotational amplitude (coin p = 0.03, CAT-pitch p < 0.001, CAT-yaw p < 0.001), trunk rotational amplitude (jacket p = 0.01, CAT-yaw p = 0.005), and head−trunk coupling (jacket p = 0.007, CAT-yaw p = 0.003) were captured by wearable sensors between the two conditions. Alterations in turning movement were detected at the head and trunk during daily living tasks. These results support the ecological validity of using wearable sensors to quantify movement alterations during real-world scenarios.
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Affiliation(s)
- Angela R. Weston
- Department of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84108, USA;
| | - Brian J. Loyd
- Department of Physical Therapy and Rehabilitation Sciences, University of Montana, 32 Campus Dr., Missoula, MT 59812, USA;
| | - Carolyn Taylor
- Department of Orthopedics, University of Utah, 590 Wakara Way, Salt Lake City, UT 84108, USA;
| | - Carrie Hoppes
- Army Baylor University Doctoral Program in Physical Therapy, U.S. Army Medical Center of Excellence, 3630 Stanley Road, San Antonio, TX 78234, USA;
| | - Leland E. Dibble
- Department of Physical Therapy and Athletic Training, University of Utah, 520 Wakara Way, Salt Lake City, UT 84108, USA;
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Sugimoto T, Sato M, Dehle FC, Brnabic AJM, Weston AR, Burge RT. Metabolic Disorders, Osteoporosis and Fracture Risk in Asia: A Systematic Review. Value Health 2014; 17:A772. [PMID: 27202845 DOI: 10.1016/j.jval.2014.08.323] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- T Sugimoto
- Shimane University Faculty of Medicine, Izumo, Shimane, Japan
| | - M Sato
- Eli Lilly Japan, Kobe, Japan
| | | | | | | | - R T Burge
- Eli Lilly and Company, Indianapolis, IN, USA
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Mernagh P, Campbell S, Dietlein M, Luster M, Mazzaferri E, Weston AR. Cost-effectiveness of using recombinant human TSH prior to radioiodine ablation for thyroid cancer, compared with treating patients in a hypothyroid state: the German perspective. Eur J Endocrinol 2006; 155:405-14. [PMID: 16914594 DOI: 10.1530/eje.1.02223] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE This investigation evaluated the cost-effectiveness of radioiodine remnant ablation following preparation with recombinant human TSH (rhTSH), compared with the standard preparation, whereby patients are rendered hypothyroid. DESIGN The economic evaluation relates to patients with well differentiated thyroid cancer who have undergone thyroidectomy, but have no metastases. The evaluation takes a societal perspective, considering costs and benefits to all parties. The benefits were expressed in units of quality-adjusted life years (QALY), so differences in life expectancy were captured with consideration of quality of life. METHODS A lifetime Markov model with Monte Carlo simulation of 100,000 patients was used to assess cost per QALY gained. The clinical inputs were sourced from a multi-centre, randomised controlled trial comparing remnant ablation success after rhTSH-preparation with hypothyroid preparation. The model applied German unit costs, however, the structure is generalisable to other jurisdictions. The additional cost of rhTSH procurement and administration is considered relative to the clinical benefits and cost offsets. These included avoidance of hypothyroidism, increased work productivity, earlier discharge from radioprotection and a theoretical reduction in the risk of secondary malignancy. The latter two benefits relate to faster radioiodine clearance after rhTSH preparation. RESULTS The additional benefits of rhTSH (0.0495 QALY) are obtained with an incremental societal cost of 47 euro, equating to an incremental cost per QALYof 958 euro. Sensitivity analyses had only a modest impact upon cost-effectiveness, with all one-way sensitivity results remaining under 15,000 euro/QALY. CONCLUSIONS The use of rhTSH prior to radioiodine ablation represents good value-for-money with the benefits to patient and society obtained at modest net cost.
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Affiliation(s)
- P Mernagh
- Health Technology Analysts Pty Ltd, PO Box 133, Balmain, Sydney 2041, Australia.
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Abstract
PURPOSE The time course of physiological exercise responses after acute ascent to moderate altitude was investigated. METHODS Fifteen young male subjects (16.5 +/- 0.8 yr) completed one familiarization and then two further sea level sessions to determine sea level values (SL). Subjects were then tested 6 h (ALT1), 18 h (ALT2), and 47 h (ALT3) after arrival at 1700 m. Subjects completed a 5-min submaximal cycle test, shuttle run test, and 45-s repeated push-up test. Hemoglobin (Hb) and hematocrit (Hct) were measured. RESULTS Cycle test heart rate (HR) was higher at ALT1 than SL (182 +/- 15 vs 177 +/- 16 b.min(-1), P < 0.01) but had returned to 177 +/- 13 and 176 +/- 12 b.min(-1) at ALT2 and ALT3, respectively. At ALT1, only five subjects completed the full 5 min. Postexercise plasma lactate was not different. Shuttle test HR was higher at ALT1 than SL (191 +/- 8 vs 185 +/- 14 b.min(-1), P = 0.01) but had returned to 185 +/- 10 and 183 +/- 16 b.min(-1) at ALT2 and ALT3. Shuttle run time (SRT) was 37% shorter at ALT1 than SL (251 +/- 134 vs 401 +/- 115 s, P < 0.001) and remained impaired at ALT2 and ALT3 (330 +/- 124 and 344 +/- 115 s, both P < 0.001 vs SL). There was a significant relationship between magnitude of increased HR and reduction in SRT between SL and ALT1 (r = 0.52, P < 0.05). Push-up HR, Hb, and Hct were not affected by altitude. CONCLUSIONS These findings indicate that detrimental effects of acute ascent to 1700 m on exercise performance are greater after 6 h than after 18 or 47 h. Performance was not entirely restored to SL values even after 47 h, despite restoration of easily measured physiological parameters. The results suggest travel to moderate altitude should occur as early as is practical before competition.
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Affiliation(s)
- A R Weston
- Department of Physiology, University of Natal Medical School, Congella, Natal 4013, South Africa.
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Crameri RM, Weston AR, Rutkowski S, Middleton JW, Davis GM, Sutton JR. Effects of electrical stimulation leg training during the acute phase of spinal cord injury: a pilot study. Eur J Appl Physiol 2000; 83:409-15. [PMID: 11138583 DOI: 10.1007/s004210000263] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Four individuals with a spinal cord injury underwent 16 weeks of isometric electrical stimulation training to both legs for 60 min, five times per week during the first 5 months after injury, while two SCI individuals remained untrained. A baseline biopsy sample of the vastus lateralis muscle was obtained within 1 month of injury, and another biopsy sample was taken after a further 16 weeks. The untrained, paralyzed skeletal muscle displayed a reduction in (1) type I fibers (from 50% to 9%), (2) myosin heavy chain (MHC) I (from 27% to 6%), and (3) fiber cross-sectional area of type I, type IIA and type IIX fibers (-62%, -68%, and -55%, respectively) when compared to the baseline sample of muscle taken within 1 month of injury. In contrast, the trained group showed smaller alterations in type I fibers (from 49% to 40%) and MHC I composition (from 39% to 25%), while fiber cross-sectional area was similar to baseline levels for type I, type IIA and type IIX fibers (-3%, -8%, and -4%, respectively). In conclusion, electrical stimulation training can largely prevent the adverse effects of a spinal cord injury upon paralyzed human skeletal muscle if applied soon after the injury.
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Affiliation(s)
- R M Crameri
- School of Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, Lidcombe, NSW, Australia.
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Abstract
PURPOSE Anecdotal evidence suggests an advantageous physiological endowment of the African endurance athlete. Higher fractional utilization of VO2max has been suggested but not measured directly, and investigations of running economy have been inconclusive. The aim of the current study was to measure a) running economy and b) fractional utilization of VO2max, in African and Caucasian 10-km runners of similar body mass. METHODS Eight African and eight Caucasian runners had no significant difference in mean race time (32.8 +/- 2.8, 32.0 +/- 2.5 min, respectively), body mass (61.4 +/- 7.0, 64.9 +/- 3.0 kg), age, body fat, or lean thigh volume. Caucasian runners were 6 cm taller (P < 0.05). Subjects completed a progressive treadmill VO2peak test. On a separate day, subjects completed two 6-min workloads (16.1 km x h(-1) and 10-km race pace) separated by 5 min. RESULTS Mean VO2peak was 13% lower in the Africans (61.9 +/- 6.9, 69.9 +/- 5.4 mL x kg(-1) x min(-1), P = 0.01). At 16.1 km x h(-1), the Africans were 5% more economical (47.3 +/- 3.2, 49.9 +/- 2.4 mL x kg(-1) x min(-1), P < 0.05). This difference increased to 8% (P < 0.01) when standardized per kg(0.66). At race pace, the Africans utilized a higher %VO2peak (92.2 +/- 3.7, 86.0 +/- 4.8%, P < 0.01) and had higher HR (185 +/- 9, 174 +/- 11 b x min(-1), P < 0.05) and plasma [ammonia] (113.2 +/- 51, 60.3 +/- 16.9 micromol x L(-1), P < 0.05). Despite the higher relative workload, the plasma [lactate] was not different (5.2 +/- 2.0, 4.2 +/- 1.7 mmol x L(-1), NS). CONCLUSIONS This study indicates greater running economy and higher fractional utilization of VO2peak in African distance runners. Although not elucidating the origin of these differences, the findings may partially explain the success of African runners at the elite level.
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Affiliation(s)
- A R Weston
- Department of Physiology, University of Cape Town Medical School, South Africa.
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Weston AR, Karamizrak O, Smith A, Noakes TD, Myburgh KH. African runners exhibit greater fatigue resistance, lower lactate accumulation, and higher oxidative enzyme activity. J Appl Physiol (1985) 1999; 86:915-23. [PMID: 10066705 DOI: 10.1152/jappl.1999.86.3.915] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nine African and eight Caucasian 10-km runners resident at sea level volunteered. Maximal O2 consumption and peak treadmill velocity (PTV) were measured by using a progressive test, and fatigue resistance [time to fatigue (TTF)] was measured by using a newly developed high-intensity running test: 5 min at 72, 80, and 88% of individual PTV followed by 92% PTV to exhaustion. Skeletal muscle enzyme activities were determined in 12 runners and 12 sedentary control subjects. In a comparison of African and Caucasian runners, mean 10-km race time, maximal O2 consumption, and PTV were similar. In African runners, TTF was 21% longer (P < 0.01), plasma lactate accumulation after 5 min at 88% PTV was 38% lower (P < 0.05), and citrate synthase activity was 50% higher (27.9 +/- 7.5 vs. 18.6 +/- 2.1 micromol. g wet wt-1. min-1, P = 0.02). Africans accumulated lactate at a slower rate with increasing exercise intensity (P < 0.05). Among the entire group of runners, a higher citrate synthase activity was associated with a longer TTF (r = 0.70, P < 0.05), a lower plasma lactate accumulation (r = -0.73, P = 0.01), and a lower respiratory exchange ratio (r = -0.63, P < 0.05). We conclude that the African and Caucasian runners in the present study differed with respect to oxidative enzyme activity, rate of lactate accumulation, and their ability to sustain high-intensity endurance exercise.
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Affiliation(s)
- A R Weston
- Medical Research Council/University of Cape Town Bioenergetics of Exercise Research Unit, Department of Physiology, Cape Town 7925, South Africa.
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St Clair Gibson A, Lambert MI, Weston AR, Myburgh KH, Emms M, Kirby P, Marinaki AM, Owen PE, Derman W, Noakes TD. Exercise-induced mitochondrial dysfunction in an elite athlete. Clin J Sport Med 1998; 8:52-5. [PMID: 9448959 DOI: 10.1097/00042752-199801000-00012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- A St Clair Gibson
- Department of Physiology, University of Cape Town Medical School, South Africa
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Weston AR, Myburgh KH, Lindsay FH, Dennis SC, Noakes TD, Hawley JA. Skeletal muscle buffering capacity and endurance performance after high-intensity interval training by well-trained cyclists. Eur J Appl Physiol Occup Physiol 1996; 75:7-13. [PMID: 9007451 DOI: 10.1007/s004210050119] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Skeletal muscle buffering capacity (beta m), enzyme activities and exercise performance were measured before and after 4 weeks of high-intensity, submaximal interval training (HIT) undertaken by six well-trained competitive cyclists [mean maximal oxygen consumption (VO2max) = 66.2 ml.kg-1.min-1]. HIT replaced a portion of habitual endurance training and consisted of six sessions, each of six to eight repetitions of 5 min duration at 80% of peak sustained power output (PPO) separated by 1 min of recovery. beta m increased from 206.6 (17.9) to 240.4 (34.1) mumol H+.g muscle dw-1.pH-1 after HIT (P = 0.05). PPO, time to fatigue at 150% PPO (TF150) and 40-km cycle time trial performance (TT40) all significantly improved after HIT (P < 0.05). In contrast, there was no change in the activity of either phosphofructokinase or citrate synthase. In addition, beta m correlated significantly with TT40 performance before HIT (r = -0.82, P < 0.05) and the relationship between change in beta m and change in TT40 was close to significance (r = -0.74). beta m did not correlate with TF150. These results indicate that beta m may be an important determinant of relatively short-duration (< 60 min) endurance cycling activity and responds positively to just six sessions of high-intensity, submaximal interval training.
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Affiliation(s)
- A R Weston
- Department of Physiology, UCT Medical School, Observatory, South Africa
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15
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Weston AR, Wilson GR, Noakes TD, Myburgh KH. Skeletal muscle buffering capacity is higher in the superficial vastus than in the soleus of spontaneously running rats. Acta Physiol Scand 1996; 157:211-6. [PMID: 8800361 DOI: 10.1046/j.1365-201x.1996.488225000.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Skeletal muscle buffering capacity (beta mtitr) was determined in soleus (type I) and superficial vastus (type II) muscles of 16 Long-Evans rats with differing levels of spontaneous activity and in 11 sedentary control rats. beta mtitr was 24% higher (P < 0.001) in superficial vastus muscle than in soleus muscle (268 +/- 50 vs. 216 +/- 30 mumol H+ g muscle dry wt-1 pH unit-1) (mean +/- SD). There was no relationship between beta mtitr and mean weekly running distance amongst spontaneously running rats, nor was beta mtitr any greater in these rats than in a group of sedentary control rats. Protein to wet wt ratio was 31% higher (P < 0.0001) in the superficial vastus muscle when compared with soleus muscle (22.04 +/- 3.74 vs. 16.77 +/- 3.00 mg protein, 100 mg wet wt muscle-1), but there was no relationship between protein to wet wt ratio and running distance. Initial muscle homogenate pH (pHi) was lower in superficial vastus muscle compared with soleus muscle (6.36 +/- 0.25 vs. 6.63 +/- 0.16). Running rats had a significantly lower pHi in both soleus and superficial vastus than sedentary controls. There was an exponential relationship between weekly running distance and pHi in both the superficial vastus muscle (r = -0.86. P < 0.001) and the soleus muscle (r = -0.73, P < 0.01). Citrate synthase activity correlated with weekly running distance in superficial vastus muscle (r = 0.66, P < 0.01) but not in soleus muscle. The results confirm a higher beta mtitr in the type II superficial vastus muscle when compared with the predominantly type I soleus muscle. We suggest that this may be partly the result of a higher protein concentration in type II muscle. Future studies measuring beta mtitr in mixed muscle (e.g. human vastus lateralis) should report fibre type composition.
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Affiliation(s)
- A R Weston
- Department of Physiology, University of Cape Town Medical School, South Africa
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16
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Abstract
Exercise capacity in patients with stable heart failure may be influenced by prolonged drug treatment or exercise training, but acute interventions are generally thought to have little effect. Cardiorespiratory responses to exercise were studied in 12 consecutive patients with chronic congestive heart failure who underwent serial submaximal and maximal exercise tests at inspired oxygen concentrations of 21% (room air), 30%, and 50%. Mean (SD) exercise duration during progressive testing to maximum exercise capacity was prolonged from 548 (276) s on room air to 632 (285) s on 50% oxygen (p = 0.012). During steady-state exercise at 45 W, oxygen enrichment to 50% was associated with significantly increased arterial oxygen saturation (94.6 [1.9]% to 97.5 [1.3]%), and significantly reduced minute ventilation (36.1 [8.6] l/min to 28.1 [5.9] l/min), cardiac output (7.5 [2.3] l/min to 6.5 [1.9] l/min), and subjective scores for fatigue and breathlessness (13.9 [3.1] to 11.5 [3.5]) compared with room air intermediate changes were observed with 30% inspired oxygen. Increased inspired oxygen concentrations can improve exercise performance acutely and modify the ventilatory response to exercise in patients with heart failure. Hyperoxia reduces ventilatory response and circulatory demand while maintaining oxygen delivery at a given workload. The potential benefits of increased inspired oxygen concentrations in the treatment of chronic heart failure merit further assessment.
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Affiliation(s)
- D P Moore
- Division of Clinical Cardiology, Royal Postgraduate Medical School, London, UK
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17
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Abstract
Questionnaires examining behaviors and attitudes related to physical activity and asthma were administered to 408 urban schoolchildren aged 11-13 years. Asthmatics (16% of the sample) were more frequently active and were more anxious prior to exercise than nonasthmatics, but did not differ significantly from nonasthmatics in enjoyment of exercise or in physical self-concept. The motives for performing exercise or sport were similar in the two groups, although the asthmatics perceived less pressure to be active from parents or school than the nonasthmatics. It is concluded that asthmatic children have favorable behaviors and attitudes in relation to exercise and sport.
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Affiliation(s)
- A R Weston
- Department of Physiology, University of Otago, Dunedin, New Zealand
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