@article{genaidy_physical_2006,
	title = {Physical Demands of Work},
	journal = {International Encyclopedia Of Ergonomics And Human Factors},
	author = {A. Genaidy and W. Karwowski and C. L. Shoaf},
	year = {2006},
	pages = {854}
},

@article{karwowski_effects_2007,
	title = {The effects of lifting instructions on the psychophysically selected lifting load limits: A need for reappraisal},
	volume = {7},
	number = {1},
	journal = {Occupational Ergonomics},
	author = {W. Karwowski and B. Sherehiy and P. R. Gaddie and T. Khalaf and P. M. Quesada},
	year = {2007},
	pages = {43--51}
},

@phdthesis{perez_prediction_2005,
	title = {Prediction of whole-body lifting kinematics using artificial neural networks},
	author = {M. A. Perez},
	year = {2005}
},

@misc{_center_1967,
	title = {Center of gravity, center of pressure, and supportive forces during human activities},
	url = {http://jap.physiology.org/cgi/content/citation/23/6/831},
	month = dec,
	year = {1967},
	howpublished = {http://jap.physiology.org/cgi/content/citation/23/6/831}
},

@article{coleman_assessment_1976,
	title = {Assessment of the physical work capacity of institutionalized mentally retarded males},
	volume = {80},
	issn = {0002-9351},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/961727},
	abstract = {Educable and trainable mentally retarded males {(N=37)} were examined for physical work capacity. Analysis of results indicated that the physical work capacity of the test population was 20 to 30\% below that cited in the literature for nonretarded subjects of similar age and sex. Evidence also suggested that developmental and maintenance programs of physical fitness were required in order for mentally retarded persons to qualify for and maintain employment on most of the manual occupational tasks cited.},
	number = {6},
	journal = {American Journal of Mental Deficiency},
	author = {A E Coleman and M M Ayoub},
	month = may,
	year = {1976},
	note = {{PMID:} 961727},
	keywords = {{Adolescent,Adult,Age} {Factors,Disability} {Evaluation,Efficiency,Heart} {Rate,Hospitalization,Intelligence,Male,Mental} {Retardation,Occupations,Oxygen,Physical} Education and {Training,Physical} {Exertion,Respiration,Work} Capacity Evaluation},
	pages = {629--35}
},

@article{lee_minimal_2003,
	title = {Minimal acceptable handling time intervals for lifting and lowering tasks},
	volume = {34},
	number = {6},
	journal = {Applied Ergonomics},
	author = {T. H. Lee},
	year = {2003},
	pages = {629--634}
},

@article{flanders_arm_1990,
	title = {Arm muscle activation for static forces in three-dimensional space},
	volume = {64},
	url = {http://jn.physiology.org/cgi/content/abstract/64/6/1818},
	number = {6},
	journal = {J Neurophysiol},
	author = {M. Flanders and J. F. Soechting},
	month = dec,
	year = {1990},
	pages = {1818--1837}
},

@article{wexler_mathematical_1997,
	title = {A mathematical model that predicts skeletal muscle force},
	volume = {44},
	issn = {0018-9294},
	doi = {10.1109/10.568909},
	abstract = {This study demonstrates the validity of a mathematical model that predicts the force generated by rat skeletal muscles during brief subtetanic and tetanic isometric contractions. The model consists of three coupled differential equations {(ODEs).} The first two equations represent the calcium dynamics and the third equation represents force dynamics. The model parameters were identified from brief trains of regularly spaces pulses [constant-frequency trains {(CFTs)]} that produce subtetanic muscle responses. Using these parameters, the model was able to predict isometric forces from other stimulation patterns. For the gastrocnemius muscles predictions were made for responses to {CFTs} with interpulse intervals {(IPI's)} ranging from 10 to 50 ms and variable-frequency trains {(VFT's),} where the initial {IPI=10} ms and the remaining {IPIs} were identical to those used for the {CFTs.} For the soleus muscles predictions were made for 10-100-ms {CFTs.} The shape of the predicted responses closely match the experimental data. Comparisons between experimental and modeled force-time integrals, peak forces, and time-to-peak also suggest excellent agreement between the model and the experiment data. Many physiological parameters predicted by the model agree with values obtained independently by others. In conclusion, the model accurately predicts isometric forces generated by rat gastrocnemius and soleus muscles produced by brief stimulation trains.},
	number = {5},
	journal = {Biomedical Engineering, {IEEE} Transactions on},
	author = {{A.S.} Wexler and Jun Ding and {S.A.} {Binder-Macleod}},
	year = {1997},
	keywords = {10 to 100 ms,biomechanics,brief stimulation trains,brief subtetanic {contractions,Ca,calcium} dynamics,constant-frequency trains,differential equations,force {dynamics,gastrocnemius,Hill-type} model,interpulse intervals,isometric forces,mathematical model,muscle,physiological models,rat skeletal muscles,regularly spaces pulses,skeletal muscle force prediction,soleus,tetanic isometric contractions},
	pages = {337--348}
},

@article{ayoub_predicint_1979,
	title = {Predicint lifting capacity},
	volume = {40},
	issn = {0002-8894},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/539547},
	abstract = {As science and technology become more sophisticated and with the rapid computation capabilities of the modern computer available, it becomes both possible and economically feasible to scientifically study man and his interaction with his working environment. It is now possible for a person seeking employment to expect and obtain a position which will not be unnecessarily hazardous to his immediate health or have detrimental effects over the long run. Manual materials handling is the contributor of over 400,000 back injuries suffered in the {U.S.} each year. This research is directed at determining the appropriate operator variables to measure for predicting the permissible weight of lift for three ranges of lift: floor to knuckle height, knuckle height to shoulder height, and shoulder height to reach height. A modified psychophysical procedure was used during which the subjects were instructed to adjust the weight in a tote box to the maximum weight they could lift repetitively without excessive strain or fatique. The task consisted of lifting loads under different conditions of task variables, namely, height of lift, frequency of lift, and load size. Industrial workers as well as students of both sexes were used as subjects. Based on the data obtained, the lifting capacity of the worker was determined for the different ranges of lift. In addition, predictive models were developed based on the operator variables and the task variables investigated.},
	number = {12},
	journal = {American Industrial Hygiene Association Journal},
	author = {M M Ayoub and R Dryden and J {McDaniel} and R Knipfer and D Dixon},
	month = dec,
	year = {1979},
	note = {{PMID:} 539547},
	keywords = {Accident {Prevention,Anthropometry,Disability} {Evaluation,Female,Male,Models,} {Biological,Occupational} {Diseases,Safety,Spinal} {Injuries,Work} Capacity Evaluation},
	pages = {1075--84}
},

@article{matheson_effect_1993,
	title = {Effect of computerized instructions on measurement of lift capacity: Safety, reliability, and validity},
	volume = {3},
	url = {http://dx.doi.org/10.1007/BF01078160},
	doi = {{10.1007/BF01078160}},
	abstract = {The evaluation of lift capacity is an important part of most functional capacity evaluations. Several different methods have been developed to evaluate lift capacity in a safe, reliable, and valid manner. Isometric strength testing is one approach which has been demonstrated to be highly reliable. However, questions have been raised about the safety and validity of isometric strength testing as a predictor of “real world” lift capacity. One method to improve safety is to provide real time performance feedback so that the evaluee is able to increase psychophysical input to appropriately gauge his or her effort level. One method to improve reliability is to provide standardized instructions that are well understood by the evaluee. Both of these approaches have been utilized in the {ERGOS} Work Simulator, a computer-controlled multiple-task evaluation instrument that presents visual and auditory instructions to the evaluee along with “real-time” performance feedback. The safety, reliability, and validity of this computer-automated approach in comparison to an experienced human evaluator was evaluated in this research project. The results of this study demonstrate the efficacy of computerized instructions in an isometric strength testing system to achieve safe, reliable, and valid results. Intra-task variability may be improved by providing pre-test practice trials.},
	number = {2},
	journal = {Journal of Occupational Rehabilitation},
	author = {Leonard N. Matheson and Rolf Danner and Janet Grant and Vert Mooney},
	month = jun,
	year = {1993},
	pages = {65--81}
},

@article{ayoub_predicint_1979-1,
	title = {Predicint lifting capacity},
	volume = {40},
	issn = {0002-8894},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/539547},
	abstract = {As science and technology become more sophisticated and with the rapid computation capabilities of the modern computer available, it becomes both possible and economically feasible to scientifically study man and his interaction with his working environment. It is now possible for a person seeking employment to expect and obtain a position which will not be unnecessarily hazardous to his immediate health or have detrimental effects over the long run. Manual materials handling is the contributor of over 400,000 back injuries suffered in the {U.S.} each year. This research is directed at determining the appropriate operator variables to measure for predicting the permissible weight of lift for three ranges of lift: floor to knuckle height, knuckle height to shoulder height, and shoulder height to reach height. A modified psychophysical procedure was used during which the subjects were instructed to adjust the weight in a tote box to the maximum weight they could lift repetitively without excessive strain or fatique. The task consisted of lifting loads under different conditions of task variables, namely, height of lift, frequency of lift, and load size. Industrial workers as well as students of both sexes were used as subjects. Based on the data obtained, the lifting capacity of the worker was determined for the different ranges of lift. In addition, predictive models were developed based on the operator variables and the task variables investigated.},
	number = {12},
	journal = {American Industrial Hygiene Association Journal},
	author = {M M Ayoub and R Dryden and J {McDaniel} and R Knipfer and D Dixon},
	month = dec,
	year = {1979},
	note = {{PMID:} 539547},
	keywords = {Accident {Prevention,Anthropometry,Disability} {Evaluation,Female,Male,Models,} {Biological,Occupational} {Diseases,Safety,Spinal} {Injuries,Work} Capacity Evaluation},
	pages = {1075--84}
},

@article{karatzaferi_force_2004,
	title = {The force exerted by a muscle cross-bridge depends directly on the strength of the actomyosin bond},
	volume = {87},
	number = {4},
	journal = {Biophysical journal},
	author = {C. Karatzaferi and M. K. Chinn and R. Cooke},
	year = {2004},
	pages = {2532--2544}
},

@article{aghazadeh_comparison_1985,
	title = {A comparison of dynamic- and static-strength models for prediction of lifting capacity},
	volume = {28},
	issn = {0014-0139},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/4076165},
	number = {10},
	journal = {Ergonomics},
	author = {F Aghazadeh and M M Ayoub},
	month = oct,
	year = {1985},
	note = {{PMID:} 4076165},
	keywords = {{Adult,Biomechanics,Male,Models,} {Biological,Weight} {Lifting,Work}},
	pages = {1409--17}
},

@article{hsiang_development_1994,
	title = {Development of methodology in biomechanical simulation of manual lifting},
	volume = {13},
	number = {4},
	journal = {International Journal of Industrial Ergonomics},
	author = {S. H. Hsiang and M. M. Ayoub},
	year = {1994},
	pages = {271--288}
},

@article{giurintano_virtual_1995,
	title = {A virtual five-link model of the thumb},
	volume = {17},
	number = {4},
	journal = {Medical Engineering and Physics},
	author = {D. J. Giurintano and A. M. Hollister and W. L. Buford and D. E. Thompson and L. M. Myers},
	year = {1995},
	pages = {297--303}
},

@article{elfeituri_biomechanics_????,
	title = {{THE} {BIOMECHANICS} {OF} {MANUAL} {LIFTING} {TASKS} {IN} {CONFINED} {WORK} {SPACES} {UTILIZING} {COMPUTER} {MODELING}},
	volume = {34},
	journal = {Age (years)},
	author = {F. E. Elfeituri and S. M. Taboun},
	pages = {5.8}
},

@phdthesis{liu_interactive_2003,
	title = {Interactive reach planning for animated characters using hardware acceleration},
	school = {University of Pennsylvania},
	author = {Y. Liu},
	year = {2003},
	comment = {neat- but didn't use true joint model of the human body? What's the deal with that? (2009-04-11)}
},

@book{_development_1981,
	title = {Development of an Atlas of Strengths and Establishment of an Appropriate Model Structure},
	year = {1981}
},

@article{selection_worker_1999,
	title = {Worker Strength Evaluation: Job Design and Worker Selection},
	journal = {The Occupational Ergonomics Handbook},
	author = {W. Selection},
	year = {1999},
	pages = {371}
},

@article{nussbaum_determination_2002,
	title = {Determination and Evaluation of Acceptable Force Limits in {Single-Digit} Tasks},
	volume = {44},
	url = {http://hfs.sagepub.com/cgi/content/abstract/44/4/545},
	doi = {10.1518/0018720024496908},
	abstract = {Acceptable limits derived from psychophysical methodologies have been proposed, measured, and employed in a range of applications. There is little existing work, however, on such limits for single-digit exertions and relatively limited evidence on several fundamental issues related to data collection and processing of a sequence of self-regulated exertion levels. An experimental study was conducted using 14 male and 10 female participants (age range 18--31 years) from whom maximal voluntary exertions and maximal acceptable limits {(MALs)} were obtained using the index finger and thumb. Moderate to high levels of consistency were found for both measures between sessions separated by one day. Single {MAL} values, determined from a time series of exertions, were equivalent across three divergent processing methods and between values obtained from 5- and 25-min samples. A critical interpretation of these and earlier results supports continued use of acceptable limits but also suggests that they should be used with some caution and not equated with safe limits. This research can be applied toward future development of exertion limits based on perceived acceptability.
},
	number = {4},
	journal = {Human Factors: The Journal of the Human Factors and Ergonomics Society},
	author = {Maury A. Nussbaum and Hope Johnson},
	year = {2002},
	pages = {545--556}
},

@article{valero-cuevas_large_1998,
	title = {Large index-fingertip forces are produced by subject-independent patterns of muscle excitation},
	volume = {31},
	number = {8},
	journal = {Journal of Biomechanics},
	author = {F. J. {Valero-Cuevas} and F. E. Zajac and C. G. Burgar},
	year = {1998},
	pages = {693--704}
},

@article{kamon_dynamic_1982,
	title = {Dynamic and static lifting capacity and muscular strength of steelmill workers},
	volume = {43},
	issn = {0002-8894},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/7168442},
	abstract = {Dynamic and static strength measurements were compared respectively to maximal actual lifting and to a static lifting strength of 228 male steelmill workers. The strength tests were reasonably correlated with the lifting measurements. The dynamic strength test was the simplest, the least time consuming, revealing one to one ratio with the maximal actual lift and was not perceived as an exerting maneuver. Therefore, when matching between the job and a worker is desirable, it is suggested to use the dynamic strength test as a predictor for lifting capacity.},
	number = {11},
	journal = {American Industrial Hygiene Association Journal},
	author = {E Kamon and D Kiser and J L Pytel},
	month = nov,
	year = {1982},
	note = {{PMID:} 7168442},
	keywords = {{Adult,Male,Metallurgy,Middle} {Aged,Muscles,Occupational} Medicine},
	pages = {853--7}
},

@article{ayoub_2-d_1998,
	title = {A {2-D} simulation model for lifting activities},
	volume = {35},
	issn = {0360-8352},
	url = {http://www.sciencedirect.com/science/article/B6V27-3WXX91K-23/2/6deb1a74427307e0c4e0b2a687c27644},
	doi = {{10.1016/S0360-8352(98)00173-9}},
	abstract = {
Occupational biomechanics models deal with the evaluation of physical activities such as lifting of loads. This allows the user to determine the stresses imposed on the musculoskeletal system while holding or moving a load. These models are useful tools in estimating these stresses especially those imposed on the lumbar spine. dynamic biomechanical models, as opposed to static models require the displacement-time information to obtain the kinematics needed to estimate the kinetics of the motion. However, the collection of this displacement data is both tedious and can require expensive equipment.
Simulation models on the other hand can provide an indirect means of performing the biomechanical analyses without having to collect the displacement-time data. A typical simulation model for {2-D} lifting activities will be presented. The basis for this is the hypothesis that the body will perform the activity in such a manner so as to minimize the work done. Using this assumption an objective function was developed subject to a set of constraints. These constraints relate to the human movement, the physical workplace layout, and maintenance of balance. Using this model, it was possible to generate the lifting motion patterns, as well as the kinematics and kinetics of motion. The paper discusses the model development, the model output and the kinematics and kinetics of the simulation of the lifting action.},
	number = {3-4},
	journal = {Computers \& Industrial Engineering},
	author = {M. M. Ayoub},
	month = dec,
	year = {1998},
	keywords = {{Biomechanics,Kinematics,Kinetics,Lifting,Optimization,Simulation}},
	pages = {619--622}
},

@article{kant_effects_2006,
	title = {Effects of Work Exposure on Maximum Acceptable Repetition Rates in a Manual Torquing Task},
	author = {R. Kant},
	year = {2006}
},

@article{davis_influence_1997,
	title = {Influence of lift moment in determining {MAWL}},
	volume = {39},
	number = {2},
	journal = {Human factors},
	author = {K. G. Davis and B. C. Kirking and L. L. Gaudes and J. Yang and W. S. Marras},
	year = {1997}
},

@article{fredericks_ergonomic_2008,
	title = {An ergonomic evaluation of a manual metal pouring operation},
	volume = {38},
	number = {2},
	journal = {International Journal of Industrial Ergonomics},
	author = {T. K. Fredericks and A. R. Kumar and S. Karim},
	year = {2008},
	pages = {182--192}
},

@article{maiti_determination_2004,
	title = {Determination of maximum acceptable weight of lift by adult Indian female workers},
	volume = {34},
	issn = {0169-8141},
	url = {http://www.sciencedirect.com/science/article/B6V31-4D4D4PP-1/2/99687ab49a296d8f8f4df1e8007104f2},
	doi = {10.1016/j.ergon.2004.06.003},
	abstract = {
A study on maximum acceptable weight limit {(MAWL)} was conducted on ten adult Indian female building construction workers {(CW)} and eight household workers {(HW),} following the psychophysical methodology. All these workers were in the age group of 28-32 years. In this study, three different body heights (i.e. knee, waist and maximum reach) in sagittal plane were considered. The lifting frequency was fixed at 1 lift min-1. The subjects were instructed to lift the load from the ground. Each set of experiments was conducted for 45 min work period using free-style lifting technique. Subjects were using a load container with no handle, which is typically used in the field. Both the working heart rates {(WHR)} and pause heart rates (with 4.4 s interval) were collected for the entire duration. The subjects were requested to rate their perceived exertion level after each load adjustment. The average {MAWL} working heart rates of {CW} group are 106.2(±8.3), 108.7(±9.3) and 106.8(±11.0) beats min-1 for knee, waist and maximum reach heights, where the load levels were estimated as 18.2(±0.8), 17.4(±1.4) and 16.3(±1.2) kg, respectively. For {HW} group, the {MAWL} working heart rates obtained were 101.3(±8.0), 99.6(±6.2) and 105.2(±6.1) beats min-1 for knee, waist and maximum reach heights and the corresponding load levels were 15.4(±0.5), 14.4(±0.7) and 13.9(±1.2) kg, respectively. Both the groups psychophysically rated the work in moderate to heavy category. A best-fit curve was obtained from average normalized baseline pause heart rates with work duration (t) as Avg. {N.H.R.base=k.t[alpha].} It has been observed that with extrapolation of the work duration to 8 h from 45 min experimental observation, the heart rate would increase to about 6-8 beats min-1 for both the groups of workers. This equation can be used to approximate the effect of work-duration on heart {rate.Relevance} to industry
{MAWL} study was performed on industrial female workers, which is rarely reported in the literature. Moreover, earlier studies were mainly conducted on the Americans. This study is focused on Indian population to compare the applicability of {NIOSH} guidelines in Indian context.},
	number = {6},
	journal = {International Journal of Industrial Ergonomics},
	author = {Rina Maiti and {G.G.} Ray},
	month = dec,
	year = {2004},
	keywords = {Heart {rate,Indian} female {workers,MAWL,Psychophysical} {rating,Work} duration},
	pages = {483--495}
},

@book{_development_1982,
	title = {Development of a Female Atlas of Strengths},
	year = {1982}
},

@article{jones_relation_1982,
	title = {The relation of muscle force and {EMG} to perceived force in human finger flexors},
	volume = {50},
	url = {http://dx.doi.org/10.1007/BF00952251},
	doi = {{10.1007/BF00952251}},
	abstract = {The relation between perceived force, the force exerted and the electromyogram {(EMG)} was examined in isometric contractions of the muscles (flexor carpi radialis and flexor digitorum sublimis) responsible for flexion of the third digit. Subjects were asked to produce a percentage of their maximum force, and the {EMG} and force produced were recorded. A curvilinear relation was found between perceived and exerted force which tended towards a horizontal asymptote at maximal forces. A similar relation was observed between perceived force and the {EMG.} A model was developed which assumed that the maximum voluntary contraction {(MVC)} and the perceived force at {MVC} are used as reference points by subjects in estimating perceived force. It proposed that there was a power relation between perceived force and the force of an isometric contraction. This model was found to describe the relation between perceived and exerted force and {EMG} well in comparison with other more complex models.},
	number = {1},
	journal = {European Journal of Applied Physiology},
	author = {L. A. Jones and I. W. Hunter},
	month = feb,
	year = {1982},
	pages = {125--131}
},

@article{erdemir_model-based_2007,
	title = {Model-based estimation of muscle forces exerted during movements},
	volume = {22},
	issn = {0268-0033},
	url = {http://www.sciencedirect.com/science/article/B6T59-4M6SG8G-1/2/f814c4a62c6619be786ea9250be7290d},
	doi = {10.1016/j.clinbiomech.2006.09.005},
	abstract = {
Estimation of individual muscle forces during human movement can provide insight into neural control and tissue loading and can thus contribute to improved diagnosis and management of both neurological and orthopaedic conditions. Direct measurement of muscle forces is generally not feasible in a clinical setting, and non-invasive methods based on musculoskeletal modeling should therefore be considered. The current state of the art in clinical movement analysis is that resultant joint torques can be reliably estimated from motion data and external forces (inverse dynamic analysis). Static optimization methods to transform joint torques into estimates of individual muscle forces using musculoskeletal models, have been known for several decades. To date however, none of these methods have been successfully translated into clinical practice. The main obstacles are the lack of studies reporting successful validation of muscle force estimates, and the lack of user-friendly and efficient computer software. Recent advances in forward dynamics methods have opened up new opportunities. Forward dynamic optimization can be performed such that solutions are less dependent on measured kinematics and ground reaction forces, and are consistent with additional knowledge, such as the force-length-velocity-activation relationships of the muscles, and with observed electromyography signals during movement. We conclude that clinical applications of current research should be encouraged, supported by further development of computational tools and research into new algorithms for muscle force estimation and their validation.},
	number = {2},
	journal = {Clinical Biomechanics},
	author = {Ahmet Erdemir and Scott {McLean} and Walter Herzog and Antonie J. van den Bogert},
	month = feb,
	year = {2007},
	keywords = {Forward {dynamics,Inverse} {dynamics,Musculoskeletal} {modeling,Optimization}},
	pages = {131--154}
},

@article{jiang_modelling_1987,
	title = {Modelling of maximum acceptable load of lifting by physical factors},
	volume = {30},
	issn = {0014-0139},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/3595550},
	number = {3},
	journal = {Ergonomics},
	author = {B C Jiang and M M Ayoub},
	month = mar,
	year = {1987},
	note = {{PMID:} 3595550},
	keywords = {{Adolescent,Adult,Body} {Constitution,Female,Male,Middle} {Aged,Models,} {Theoretical,Physical} {Exertion,Sports,Weight} {Lifting,Work} Capacity Evaluation},
	pages = {529--38}
},

@article{graves_quantitative_1990,
	title = {Quantitative assessment of full range-of-motion isometric lumbar extension strength},
	volume = {15},
	number = {4},
	journal = {Spine},
	author = {J. E. Graves and M. L. Pollock and D. M. Carpenter and S. H. Leggett},
	year = {1990},
	pages = {289--294},
	comment = {awesome
}
},

@article{komura_calculation_????,
	title = {Calculation and visualization of the dynamic ability of the human body},
	author = {T. Komura and Y. Shinagawa and T. L. Kunii}
},

@article{nussbaum_muscle_1995,
	title = {Muscle lines-of-action affect predicted forces in optimization-based spine muscle modeling},
	volume = {28},
	issn = {0021-9290},
	url = {http://www.sciencedirect.com/science/article/B6T82-3YGTT1R-3N/2/3176d7ba1fd065aeea2f16975ef06888},
	doi = {{10.1016/0021-9290(94)00078-I}},
	abstract = {
This study describes the effects of varied torso muscle geometries commonly assumed in optimization-based muscle force prediction models. Specifically, the sensitivity of predicted muscle and spinal forces to assumed muscle lines-of-action {(LOA)} is systematically examined. The practical significance of varied muscle {LOAs} is addressed by determining the relative precision needed for individual muscle {LOAs} and assessing which muscles are more critical to accurate prediction of spinal forces. To perform this analysis a nonlinear optimization model was used to generate muscle force predictions during combined frontal and sagittal plane moment loadings with an assumed erect posture. The {LOAs} of the erector spinae, rectus abdominus, internal and external oblique, and latissimus dorsi were systematically varied in the frontal and sagittal planes over an anatomically feasible range. The results indicated that moderate changes in the assumed {LOA} could substantially after the magnitudes of predicted muscle and spinal forces. The estimated activity level of a muscle, as well as the predicted active/silent state could be affected by the {LOA} of that muscle and others. The patterns of predicted muscle activity, with respect to load orientation, underwent only minor alterations with changing {LOA.} The relative activation of several muscles, however, was dependent on {LOA,} and frequently led to variations in predicted spinal compression ({\textgreater} 100 N change) and shear forces ({\textgreater} 50 N change). This dependence of estimated spinal forces on assumed muscle geometry was most pronounced for the obliques and minimal for the more vertically oriented muscles and when loads were sagittally symmetric. This study suggests that muscle {LOAs} are critical inputs when interpreting absolute muscle and spinal force values predicted by models of physical exertions.},
	number = {4},
	journal = {Journal of Biomechanics},
	author = {Maury A. Nussbaum and Don B. Chaffin and Catherine J. Rechtien},
	month = apr,
	year = {1995},
	pages = {401--409}
},

@article{chinn_effect_2000,
	title = {The effect of polyethylene glycol on the mechanics and {ATPase} activity of active muscle fibers},
	volume = {78},
	number = {2},
	journal = {Biophysical Journal},
	author = {M. K. Chinn and K. H. Myburgh and T. Pham and K. {Franks-Skiba} and R. Cooke},
	year = {2000},
	pages = {927--939}
},

@article{murray_center_1967,
	title = {Center of gravity, center of pressure, and supportive forces during human activities},
	volume = {23},
	number = {6},
	journal = {Journal of Applied Physiology},
	author = {M. P. Murray and A. Seireg and R. C. Scholz},
	year = {1967},
	pages = {831--838}
},

@misc{__????
}