4 technologies to enhance sporting performance

As well as a good pair of run­ning shoes, a well-fit­ting sports bra that effi­cient­ly sup­ports the breasts is impor­tant for female run­ners. It can help reduce breast pain and improve per­for­mance. When the breasts are not prop­er­ly sup­port­ed, the body com­pen­sates by pro­tect­ing them in oth­er ways. This com­pen­sa­tion can reduce run­ning per­for­mance, increase the risk of injury and even lead to back and chest pain.

To bet­ter under­stand the role of a good sports bra on the bio­me­chan­ics of run­ning, a team of researchers led by Dou­glas Pow­ell and Hai­ley Fong from the Breast Bio­me­chan­ics Research Cen­ter at the Uni­ver­si­ty of Mem­phis (USA) stud­ied how wear­ing a bra impacts knee joint stiff­ness dur­ing exer­cise. This bio­me­chan­i­cal mea­sure­ment pro­vides infor­ma­tion on the resis­tance of the knee joint to an applied force. To do this, the researchers recruit­ed 12 non-pro­fes­sion­al female run­ners aged 18–35 and had them wear two dif­fer­ent sports bras: one with high sup­port and the oth­er with low sup­port. A con­trol group did not wear a bra at all.

Each par­tic­i­pant ran on a tread­mill equipped with force detec­tors for three min­utes. The researchers filmed the run­ners using a 10-cam­era motion cap­ture sys­tem. Retrore­flec­tive mark­ers placed on the run­ners’ bod­ies also tracked their move­ments. The researchers then used soft­ware that they had spe­cial­ly devel­oped in this work to cal­cu­late the excur­sions of the knee joint (flex­ions, exten­sions and rota­tions) on the basis of the images they obtained. They also mon­i­tored chest move­ment dur­ing the exercise.

The exper­i­ments revealed that when breast sup­port was high­er, the knee joint was more rigid, thanks to small­er joint excur­sions. Com­pared with the con­trol group, the low- and high-con­tain­ment bras increased knee joint stiff­ness by 2% and 5% respec­tive­ly. Over­all, a high sup­port sports bra appeared to improve run­ning per­for­mance by 7%. The research also revealed that improve­ments in run­ning per­for­mance with high sup­port sports bras was strong­ly cor­re­lat­ed with breast size: women with larg­er breasts ben­e­fit­ed more in terms of run­ning performance.

Over the last 50 years, bra design has changed lit­tle, explains Dou­glas Pow­ell: “our results, com­bined with those of pre­vi­ous stud­ies, show that sports bras should be con­sid­ered not just as appar­el, but as sports equip­ment in their own right.”¹².

In top-lev­el sport, a frac­tion of a sec­ond can make all the dif­fer­ence. Made-to-mea­sure insoles can improve sport­ing per­for­mance and researchers at Empa, ETH Zurich and EPFL, all in Switzer­land, have devel­oped a device that is much more sophis­ti­cat­ed than a sim­ple insert. The new insole com­pris­es pres­sure and shear sen­sors that can mea­sure these para­me­ters direct­ly on the sole of the foot dur­ing any type of phys­i­cal activity.

“The pres­sures record­ed can be used to deter­mine whether a per­son is walk­ing, run­ning, or climb­ing stairs. It’s even pos­si­ble to deter­mine whether they’re car­ry­ing a heavy load on their back, in which case the pres­sure shifts more towards the heel,” explains Gilber­to Siqueira, project leader and researcher at Empa and ETH’s Com­plex Mate­ri­als Laboratory.

The soles were fab­ri­cat­ed using a 3D print­er, known as an extrud­er. The base of the sole is made from a mix­ture of sil­i­cone and cel­lu­lose nanopar­ti­cles. A con­duc­tive ink con­tain­ing sil­ver is then print­ed atop this first lay­er. The sen­sors, which are piezo­elec­tric, con­vert mechan­i­cal pres­sure into elec­tri­cal sig­nals. These are print­ed on the con­duct­ing part of the sole, where the pres­sure exert­ed by the foot is great­est. The ensem­ble is pro­tect­ed by a final lay­er of sil­i­cone. An inter­face for read­ing the sig­nals gen­er­at­ed, insert­ed into the sole, com­pletes the device.

As well as Empa, ETH Zurich and EPFL, the Cen­tre Hos­pi­tal­ier Uni­ver­si­taire Vau­dois (CHUV) and the ortho­pe­dics com­pa­ny Numo were also involved in this work. Such insoles could be used by ath­letes to mea­sure their progress dur­ing train­ing and their per­for­mance in gen­er­al³.

Researchers at the Insti­tute of Basic Sci­ence (IBS) in South Korea have devel­oped a new tis­sue pros­the­sis made from a con­duc­tive hydro­gel that can be inject­ed direct­ly into an injured mus­cle to regen­er­ate it and recon­nect it to the ner­vous sys­tem. This pros­the­sis has enabled rats with torn hind limbs to walk again.

Mus­cle injuries such as strains or tears are com­mon sports injuries. When a mus­cle is torn, its elec­tri­cal com­mu­ni­ca­tion with the ner­vous sys­tem is dis­rupt­ed and it no longer func­tions prop­er­ly. Today, these injuries can be treat­ed using portable or implantable elec­tron­ic devices. How­ev­er, these devices are rigid and inflex­i­ble, which makes them incom­pat­i­ble with soft bio­log­i­cal tis­sue. Not only are these devices uncom­fort­able for the patient, they can even cause inflam­ma­tion, which slows the heal­ing process.

The researchers’ flex­i­ble pros­the­sis com­pris­es a hydro­gel con­tain­ing hyaluron­ic acid – a nat­ur­al poly­sac­cha­ride with mechan­i­cal prop­er­ties sim­i­lar to those of soft tis­sue and known for its regen­er­a­tive prop­er­ties. To make the pros­the­sis elec­tri­cal­ly con­duct­ing, they added, via cova­lent bonds, chem­i­cal com­pounds to it con­tain­ing hexag­o­nal rings that can accom­mo­date gold nanopar­ti­cles. Gold is also bio­com­pat­i­ble and intrin­si­cal­ly chem­i­cal­ly inert.

When the gel is inject­ed into the mus­cle tis­sue of a rat, the chem­i­cal bonds it con­tains are bro­ken. They quick­ly re-form once the hydro­gel is fixed in the mus­cle, how­ev­er. It is this inno­v­a­tive chem­istry that enables it to regen­er­ate dam­aged tis­sue. What is more, the gel does not over­ac­ti­vate the animal’s immune sys­tem. It there­fore does not pro­duce fibrous scar tis­sue, as can be the case with con­ven­tion­al implantable prostheses.

The researchers found that the hydro­gel adheres to the periph­er­al nerves of the injured mus­cles in the rat’s hind leg. This means that the device can be con­nect­ed to elec­tri­cal wires and the sci­en­tists are able to acti­vate the mus­cle by send­ing elec­tri­cal stim­u­la­tion through the gel. Repeat­ed stim­u­la­tion enabled the rodents to walk short­ly after an injury.

Ulti­mate­ly, the researchers would like to apply their tech­nique to human mus­cle. How­ev­er, before they can do this, they will need to car­ry out stud­ies on ani­mals larg­er than rodents to deter­mine whether the hydro­gel can con­duct elec­tric­i­ty over longer dis­tances⁴.

Researchers in France have mea­sured the speed of pro­gres­sion, rota­tion and rebound angle of a table ten­nis ball off a glass sur­face. Led by Jean-Christophe Gémi­nard, CNRS research direc­tor at the physics lab­o­ra­to­ry of the ENS in Lyon, the sci­en­tists fired the ball onto a glass plate while vary­ing the angle and impact speed of the ball. They then mea­sured the above para­me­ters by analysing videos of how the ball inter­act­ed with the plate.

The result: at angles of inci­dence typ­i­cal­ly less than 45 degrees, the ball rolled (with­out slid­ing along the sur­face of the plate) com­plet­ing a frac­tion of a full turn, that is, less than one turn, before rebound­ing. At high­er angles of inci­dence, the ball still slid as it left the sur­face, reduc­ing its rota­tion after the bounce. The researchers explain that when bounc­ing off a sol­id sur­face, such as a glass plate, the final rota­tion, speed and bounce angle of the ball are gov­erned sole­ly by the fric­tion between the ball and the sur­face. This result, they say, would be the same for a ball bounc­ing off a real ping-pong table.

To make their exper­i­ments more real­is­tic, Jean-Christophe Gémi­nard and his col­leagues then repeat­ed them using a rack­et cov­ered with a stack of foam and elas­tomer. To a cer­tain extent, this sce­nario pre­vent­ed the ball from slid­ing over the sur­face of the glass plate. Play­ers capa­ble of repro­duc­ing the tech­niques described in this study will undoubt­ed­ly have a sig­nif­i­cant advan­tage, say the researchers.

Final­ly, the sci­en­tists repro­duced their exper­i­ments on sur­faces com­mon­ly used by table-ten­nis play­ers in the real world, but to date the results of this part of their work have not yet been made pub­lic⁵⁶.

Isabelle Dumé