Please register and log-in to create and edit pages

User Tools

    Please register and log-in to create and edit pages

Site Tools

Main Menu

Main menu
Click categories to expand

Other categories

Also see

Importance Ratingsplugin-autotooltip__plain plugin-autotooltip_bigImportance ratings

In a departure from the usual Wiki format, Wikenigma assigns 'Importance Ratings' to some pages.

The idea is to separate articles which are considered (by the editors) to cover exceptionally important unknown issues from those which (although also u…

Newsplugin-autotooltip__plain plugin-autotooltip_bigNews

[ newest at the top ]

• Jan 2021 : A milestone of 600 unknown articles has been reached.

• Oct 2020 : A milestone of 500 unknown articles has been reached.

• Aug 2020 : Currently (beta) testing the new 'WYSIWYG' (What You See Is What You Get

Contactsplugin-autotooltip__plain plugin-autotooltip_bigContacts

Use this form to send a message to Wikenigma . . . [ * note: all fields must be completed ]

Legalplugin-autotooltip__plain plugin-autotooltip_bigLegal

Content in general

Please note that in common with other publicly editable wikis, this website is not responsible for content posted by the public. Nevertheless, the ongoing editing process should be able to remove unsuitable content in a reasonable time. If you…

Donate/Sponsorplugin-autotooltip__plain plugin-autotooltip_bigDonate to Wikenigma . . .

The best way to donate is by adding new original content !

That can either be by contributing to an existing article, or by creating a new page with an as-yet-unlisted 'Known Unknown'.

Any registered user can create content.

Registerplugin-autotooltip__plain plugin-autotooltip_bigRegistration

At present, only registered users can create and edit articles.

If you'd like to register as a contributor, please request a password.

When filling in the form, make sure you supply a valid e-mail address, as the login password will be sent to that addre…

Wikenigma supports:

A-Z listingplugin-autotooltip__plain plugin-autotooltip_bigA-Z listing

This is an alphabetical index of all content pages.

rss / xml feed
sitemap file

Wikenigma - an Encyclopaedia of Unknowns Wikenigma - an Encyclopaedia of the Unknown Science

Arm swinging (in human walking)

In general, humans tend to swing their arms in sync (but out-of-phase) with their walking strides. Although the muscle-driven arm swinging must incur at least some energy costs, three recent experimental studies have shown that not swinging actually increases the overall energy costs of walking.

Several hypotheses have been proposed to explain arm-swing, and its energy cost/benefits, but as yet there is no general agreement.

“Independent of how arm swing is executed, it appears to play an important part during human locomotion. However, what this role is exactly, is still unknown. Several hypotheses have been formulated, among which:
(a) reducing vertical displacement of the center of mass (COM) (Hinrichs, 1990; Murray et al., 1967; Pontzer et al., 2009;
(b) reducing angular momentum around the longitudinal axis (Bruijn et al., 2008; Bruijn et al., 2011; Collins et al., 2009a; Elftman, 1939; Hinrichs, 1990; Park, 2008);
(c ) reducing angular movement around the longitudinal axis (Fernandez Ballesteros et al., 1965; Murray et al., 1967; Pontzer et al., 2009);
(d) reducing the ground reaction moment (GRM) (Collins et al., 2009a; Li et al., 2001; Witte et al., 1991);
(e) increasing (local) stability (Ortega et al., 2008) / balance recovery after perturbations (Bruijn et al., 2010; Hof, 2007; Marigold et al., 2002; Pijnappels et al., 2010);
(f) facilitating leg movement (Meyns et al., 2013) and;
(g) minimizing energetic costs (Collins et al., 2009a; Ortega et al., 2008; Umberger, 2008).
These hypotheses cannot be seen entirely separate from each other, and are in some cases even entirely interdependent.”

Source: Influence of arm swing on cost of transport during walking in Biology Open 2019, May 2019.

    Share this page :


Dear reader : Do you have any suggestions for the site's content?

Ideas for new topics, and suggested additions / corrections for old ones, are always welcome.

If you have skills or interests in a particular field, and have suggestions for Wikenigma, get in touch !

Or, if you'd like to become a regular contributor . . . request a login password. Registered users can edit the entire content of the site, and also create new pages.

( The 'Notes for contributors' section in the main menu has further information and guidelines etc.)

Show another (random) page